Stylus for electronic devices

ABSTRACT

A user input system including a stylus and an electronic device. A user may manipulate the stylus across an input surface of the electronic device and the movement may be detected using axially-aligned electric fields generated by the stylus. The stylus may also include a force-sensitive structure that can be used to estimate a force applied to the electronic device by the stylus.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a nonprovisional patent application of, and claimsthe benefit to, U.S. Provisional Patent Application No. 62/215,620,filed Sep. 8, 2015 and titled “Stylus For Electronic Devices,” and toU.S. Provisional Patent Application No. 62/309,816, filed Mar. 17, 2016and titled “Stylus For Electronic Devices,” the disclosures of which arehereby incorporated herein in their entirety.

FIELD

Embodiments described herein are directed to user input systems forelectronic devices, and, more particularly, to a high-precision stylusoperable with a touch screen of an electronic device.

BACKGROUND

An electronic device can integrate a touch sensor into a display tofacilitate a user's interaction with elements shown on the display. Whenthe user touches the display with one or more fingers, the touch sensorprovides the location of each touch to the electronic device which, inturn, can cause elements shown on the display (such as icons, buttons,keys, toolbars, menus, pictures, sprites, applications, documents,canvases, maps, and so on) to change. In some instances, a user mayprefer to interact with the display using an instrument that is moreprecise than the user's finger, such as a stylus.

However, a conventional stylus often provides only marginally enhancedprecision to the user because conventional touch-sensitive electronicdevices are configured, primarily, to detect the presence and locationof the user's finger. For example, many conventional touch-sensitiveelectronic devices may be unable to reliably distinguish between inputfrom the stylus and intentional or accidental input from the user'spalm, wrist, or fingers.

In other cases, to accommodate stylus input, some conventionalelectronic devices may incorporate a separate input sensor, such as anelectromagnetic digitizer, specifically dedicated to receiving inputfrom a stylus that generates a magnetic field. However, these additionalcomponents often increase the cost and complexity of manufacturing ofthe electronic device, in addition to increasing the thickness and powerconsumption of the electronic device.

SUMMARY

Embodiments described herein generally reference a stylus, including atleast a body and a tip. The tip can be disposed at a first end of thebody. The tip can be configured to emit an electric field to be detectedby an electronic device. Additionally, the tip is configured to receivea force when the tip touches the electronic device. Control circuitrymay be positioned within the body. The control circuitry is configuredto produce an electrical signal used to generate the electric field. Aforce-sensitive structure is positioned also within the body and isconfigured to produce a non-binary output in response to the force.Lastly, a rigid conduit within the body electrically couples the controlcircuitry to the tip and mechanically transfers the force to theforce-sensitive structure.

Some embodiments may include a configuration in which the externaldevice may be configured to detect a location of the tip based on thelocation of the electric field. Some embodiments may reference theelectric field as a first electric field and may also include at least aring-shaped element disposed about the rigid conduit. The ring-shapedelement may be configured to emit a second electric field. Someembodiments may include a configuration in which the external device isconfigured to detect an angular position of the stylus using the secondelectric field.

Some embodiments may also include a flexible circuit electricallycoupling circuitry within or coupled to the force-sensitive structure tocircuitry positioned within the body and circuitry behind theforce-sensitive structure. The flexible circuit includes an articulatedregion configured to flex in response to movement of the force-sensitivestructure. Some embodiments may include a configuration in which eitheror both of the circuits can include two or more substrates attached by afolded flexible connection.

Some embodiments may also include at least a cylindrical chassispositioned within the body of the stylus and having a round innervolume. A battery can be attached to the chassis and positioned withinthe round inner volume. The battery can include at least one foldedelectrode pair.

Some embodiments may include a configuration in which the rigid conduitincludes an array of conducting traces formed along a length of therigid conduit. For example, the array of conducting traces can be formedin alternatingly offset rows. In these and related embodiments, therigid conduit includes a notched via that extends from an outer surfacethereof to one or more conducting traces of the array of conductingtraces.

Some embodiments may include a configuration in which the rigid conduitincludes a first set of conductors configured to transmit a tip signal,a second set of conductors configured to transmit a ring signal, and aset of ground conductors positioned between the first and second sets.

Embodiments described herein generally reference a stylus, including atleast a body and a tip disposed at a first end of the body, andincluding at least a bulb configured to emit an electric field to bedetected by an electronic device, and a coating formed around the bulbhaving a hardness that may be less than the bulb. In other cases, thestylus can include a coating formed around the bulb having a hardnessthat is less than an input surface of the electronic device.

Some embodiments may include a configuration in which the electric fieldmay be a first electric field having a half-power point at a firstradius, and the stylus further includes a conductive ring positionedbehind the bulb and configured to emit a second electric field having ahalf-power point at a second radius that may be different than the firstradius. Some embodiments may include a configuration in which either thefirst electric field or the second electric field may be substantiallyspherical for a portion of the field that may be configured to intersectthe electronic device. Some embodiments may include a configuration inwhich the tip may be removable from the body by a threaded connection.

Some embodiments may include a configuration in which the bulb has aroot portion that extends toward the body and may be in electricalcommunication with a signal generator. Some embodiments may include aconfiguration in which the coating may be formed from a polymer materialthat may be formed using an over-molding process.

Some embodiments may include a configuration in which the coatingincludes a first inner shot formed from a first polymer material, and asecond outer shot formed from a second polymer material. Someembodiments may include a configuration in which the second polymermaterial may be softer than the first polymer material. In someembodiments, the first inner shot includes a fiber-reinforced polymermaterial, and the second polymer material of the second outer shot maybe substantially free of fibers.

Some embodiments may include a configuration in which the body may beformed from a hollow tube. A signal generator may be disposed within thetube and operatively coupled to the bulb. In these cases, the tip andthe bulb are configured to be removed from the body and the drivercircuit via a threaded connection.

Embodiments described herein generally reference a hand-held user inputdevice, including at least: a body; a tip disposed at a first end of thebody and configured to receive a force; and a force-sensitive structuredisposed within the body and including at least: a first cantileveredleg having a first edge fixed with respect to the body, a secondcantilevered leg approximately parallel to the first cantilevered legand having a second edge fixed with respect to the body, and a lateralbed extending between and connecting the first cantilevered leg and thesecond cantilevered leg. A strain-sensitive element can be attached tothe first cantilevered leg. The first cantilevered leg may be configuredto deflect in response to the force received by the tip.

Some embodiments may include a configuration in which the tip may bemechanically coupled to the lateral bed. In some cases, the mechanicalcoupling is provided by a rigid signal conduit disposed between the tipand the lateral bed. Some embodiments may include a configuration inwhich the second cantilevered leg may be configured to deflect inresponse to the force received by the tip. Some embodiments may includea configuration in which the first cantilevered leg may be configured todeflect along a serpentine curve in response to the force received bythe tip. Some embodiments may also include at least two or morestrain-sensitive elements attached to a surface of the firstcantilevered leg, wherein one or more strain-sensitive elements areplaced in a tensile strain in response to the force, and one or moreother strain-sensitive elements are placed in compressive strain inresponse to the force.

Some embodiments may also include at least sensor circuitry operativelycoupled to the two or more strain-sensitive elements and configured toproduce an output based on a difference between the tensile strain andthe compressive strain resulting from the force on the tip.

Some embodiments may include a configuration in which at least a portionof the sensor circuitry may be disposed between the first and lateralbed, and the sensor circuitry may be fixed with respect to the secondcantilevered leg. Some embodiments may include a configuration in whichthe tip transmits the force to the body through the force-sensitivestructure. Some embodiments may include a configuration in which a firstedge of the first cantilevered leg may be welded to a tube member, athird edge of the lateral bed may be welded to the tube member, and thetube member may be disposed within and attached to the body.

Embodiments described herein generally reference a stylus, including atleast a body, a tip disposed at a first end of the body and configuredto receive a force, an intermediate member positioned within the bodyand operatively coupled to the tip to transfer the force received at thetip, and a force-sensitive structure disposed within the body andincluding at least two legs having respective edges fixed with respectto the body, a lateral member extending between the two legs andoperatively coupled to the intermediate member, and a strain-sensitiveelement attached to a first leg of the two legs, wherein the first legmay be configured to deflect in response to the force received at thetip.

Some embodiments may also include at least a sleeve disposed within thebody, and wherein the two legs are welded to an interior surface of thesleeve. Some embodiments may include a configuration in which the twolegs extend from opposite sides of the lateral member.

Some embodiments may also include at least two or more strain-sensitiveelements attached to a surface of the first leg, wherein one or morestrain-sensitive elements are placed in a tensile strain in response tothe force, and one or more other strain-sensitive elements are placed incompressive strain in response to the force. Embodiments describedherein generally reference a stylus including at least: a body; a tippositioned at a first end of the body but not fixed with respect to thefirst end of the body and configured to receive a force; aforce-sensitive structure positioned within the body, theforce-sensitive structure including at least: a box structure includingat least a first and lateral bed positioned transverse to an axis of thebody, a second cantilevered leg extending between the first and secondcantilevered leg. In these embodiments, the second cantilevered leg maybe configured to shift with respect to the body in response to theforce.

Some embodiments may include a configuration in which the box structurefurther includes a side formed by a portion of a sleeve positionedwithin the body, which may be fixed with respect to the body, and thesecond side may be configured to shift with respect to the side alongthe axis of the body in response to the force. Some embodiments mayinclude a configuration in which the first and second sides areconfigured to deflect in response to the force. In many cases, thesecond side deflects into a serpentine-shaped profile.

Some embodiments are directed to a stylus as substantially describedherein. Some embodiments are directed to an electronic device assubstantially described herein. Some embodiments are directed to amethod of operating the stylus and the electronic device as describedherein. Some embodiments are directed to a method of communicationbetween the stylus and the electronic device. Some embodiments aredirected to a method of locating the stylus on an input surface of theelectronic device. Some embodiments are directed to a method ofestimating whether to enter or exit a low power state performed by thestylus. Some embodiments are directed to a method of estimating theangular position of the stylus relative to an input surface of theelectronic device.

Some embodiments are directed to a method of measuring the force appliedby the stylus to an input surface of the electronic device. Someembodiments are directed to a method of measuring, performed by thestylus, the force applied by the stylus to an input surface of theelectronic device. Some embodiments are directed to a method ofmeasuring, performed by the electronic device, the force applied by thestylus to an input surface of the electronic device. Some embodimentsare directed to a nosepiece for the stylus that is removable via athreaded connection. Some embodiments are directed to a nosepiece forthe stylus that includes a bulb-shaped electric field generator at thetip of the nosepiece. Some embodiments are directed to a nosepiece,wherein the bulb-shaped electric field generator is a pogo pin. Someembodiments are directed to a main control board for the stylus that isformed by folding two or more circuit boards over one another such asdescribed herein. Some embodiments are directed to a blind cap for thestylus. Some embodiments are directed to the blind cap, furthercomprising a pressure release vent. Some embodiments are directed to theblind cap, further comprising a permanent magnet that is configured toattract a plug extending from the stylus.

BRIEF DESCRIPTION OF THE FIGURES

Reference will now be made to representative embodiments illustrated inthe accompanying figures. It should be understood that the followingdescriptions are not intended to limit the embodiments to one preferredembodiment. To the contrary, it is intended to cover alternatives,modifications, and equivalents as may be included within the spirit andscope of the described embodiments as defined by the appended claims.

FIG. 1A depicts an electronic device with a touch-sensitive display (an“input surface”) that is configured to receive input from a stylus.

FIG. 1B depicts the stylus of FIG. 1A, oriented normal to the inputsurface of the electronic device.

FIG. 1C depicts a top view of the electronic device and stylus of FIG.1A, specifically showing the stylus oriented at an angle relative to theplane of the input surface and, in particular, an azimuthal angle of thestylus relative to a horizontal axis of the plane of the input surface.

FIG. 1D depicts a side view of the electronic device and stylus of FIGS.1A and 1C, specifically showing a polar angle of the stylus relative tothe plane of the input surface of the electronic device.

FIG. 2A depicts a simplified block diagram of a user input systemincluding a stylus and an electronic device.

FIG. 2B depicts a simplified block diagram of the stylus of the userinput system of FIG. 2A.

FIG. 2C depicts a simplified block diagram of the electronic device ofthe user input system of FIG. 2A and may be configured to receive inputfrom the stylus of FIG. 2B.

FIG. 2D depicts a simplified block diagram of a coordination engine ofthe stylus of FIG. 2B.

FIG. 2E depicts a simplified block diagram of a processing unit and awireless interface of the stylus of FIG. 2B.

FIG. 2F depicts a simplified block diagram of a power subsystem of thestylus of FIG. 2B.

FIG. 3A depicts an exploded view of various components and subsystems ofa stylus such as described herein (e.g., the stylus of the user inputsystem depicted in FIGS. 1A-1D, a stylus having the subsystems depictedin FIGS. 2D-2F, and so on).

FIG. 3B depicts the stylus of FIG. 3A, assembled, specifically showingthe stylus in a ready state in which a clearance gap separates a tip anda body of the stylus in the absence of a reaction force acting on thetip.

FIG. 3C depicts the stylus of FIG. 3B, specifically showing the stylusin an input state in which the clearance gap is partially or entirelyclosed as a result of a reaction force acting on the tip when the stylusis pressed against a surface, such as the display of the electronicdevice depicted in FIGS. 1A-1C.

FIG. 3D depicts the stylus of FIG. 3A assembled, presenting a barrel, anib, and a blind cap of the stylus in phantom, while depicting aninternal chassis of the stylus as partially transparent.

FIG. 3E depicts a detailed view of a tip end of the assembled stylus ofFIG. 3D.

FIG. 3F depicts a detailed view of a barrel section of the assembledstylus of FIG. 3D.

FIG. 3G depicts a detailed view of an end section of the assembledstylus of FIG. 3D.

FIG. 4A depicts a side view of a coordination engine of a stylus such asdescribed herein, showing a force-sensitive structure that supports atip of the stylus and, in particular, showing the force-sensitivestructure in a nominal state generally characterized by the absence of areaction force acting on the tip.

FIG. 4B depicts a side view of the coordination engine of FIG. 4A,showing the force-sensitive structure and tip in a deflected stategenerally characterized by the presence of a reaction force that acts onthe tip when the stylus is pressed against a surface, such as thedisplay of the electronic device depicted in FIGS. 1A-1C.

FIG. 4C depicts a side view of the coordination engine of FIG. 4A,particularly showing a deflected state of another force-sensitivestructure.

FIG. 4D depicts a cross-section view of the coordination engine of FIG.4A, taken through line A-A, particularly showing an example of amechanical coupling between the tip of the stylus and theforce-sensitive structure.

FIG. 4E depicts a side view of one example force-sensitive structure ina nominal state.

FIG. 4F depicts a side view of another force-sensitive structure in anominal state.

FIG. 4G depicts a side view of yet another force-sensitive structure ina nominal state.

FIG. 4H depicts a side view of another example force-sensitive structurein a nominal state.

FIG. 4I depicts a side view of another force-sensitive structure in anominal state.

FIG. 4J depicts a side view of yet another force-sensitive structure ina nominal state.

FIG. 4K depicts a back view of the force-sensitive structure of FIG. 4A,viewed along line B-B, particularly showing a distribution ofstrain-responsive elements coupled to the force-sensitive structure.

FIG. 4L depicts a back view of another force-sensitive structure in anominal state, particularly showing an example distribution ofstrain-responsive elements coupled to the force-sensitive structure.

FIG. 4M depicts a back view of yet another force-sensitive structure ina nominal state, particularly showing an example distribution ofstrain-responsive elements coupled to the force-sensitive structure.

FIG. 5A depicts a side assembly view of a coordination engine of astylus, particularly showing a signal conduit disposed within a hollowportion of a tubular and rigid electromagnetic shield.

FIG. 5B depicts an assembled view of the coordination engine of FIG. 5A,particularly illustrating electric fields that may be generated atdifferent field strengths from offset point sources of the coordinationengine of FIG. 5A.

FIG. 5C depicts the coordination engine of FIG. 5B, particularlyillustrating example electric fields that may be generated at similarfield strengths from offset point sources of the coordination engine ofFIG. 5A.

FIG. 5D depicts a cross-section view of the coordination engine of FIG.5B, taken through line C-C, particularly illustrating the signal conduitdisposed within the hollow portion of the tubular and rigidelectromagnetic shield.

FIG. 5E depicts a cross-section view of the signal conduit of FIG. 5D,taken along line D-D, showing a circuit board and signal lines disposedwithin the signal conduit.

FIG. 5F depicts a cross-section view of the signal conduit of FIG. 5D,viewed along line E-E, showing a circuit board and signal lines disposedwithin the signal conduit.

FIG. 5G depicts a side view and a top view of a stylus oriented normalto an input surface of an electronic device, the stylus configured togenerate a tip field and a ring field of different magnitudes from a tipend of the stylus, each field intersecting the plane of the inputsurface and defining a tip field intersection area and a ring fieldintersection area.

FIG. 5H depicts a side view and a top view of the stylus of FIG. 5G,particularly illustrating the relative position of the tip fieldintersection area and the ring field intersection area when the stylusis oriented at an angle relative to the plane of the input surface ofthe electronic device.

FIG. 5I depicts a side view and a top view of the stylus of FIG. 5G,particularly illustrating the relative position of the tip fieldintersection area and the ring field intersection area when the stylusis oriented at a different angle relative to the plane of the inputsurface of the electronic device.

FIG. 5J depicts a side view and a top view of the stylus of FIG. 5G,particularly illustrating the azimuthal angle and polar angle of thestylus relative to the plane of the input surface of the electronicdevice.

FIG. 5K depicts a side view of a stylus generating a tip field and aring field of similar magnitudes from a tip end of the stylus, thefields each intersecting an input surface of an electronic device,particularly illustrating the relative position of a tip fieldintersection area and a ring field intersection area when the stylus isoriented normal relative to the plane of the input surface of theelectronic device.

FIG. 5L depicts the stylus of FIG. 5K, particularly illustrating therelative position of the tip field intersection area and the ring fieldintersection area when the stylus is oriented at an angle relative tothe plane of the input surface of the electronic device.

FIG. 5M depicts the stylus of FIG. 5K, particularly illustrating therelative position of the tip field intersection area and the ring fieldintersection area when the stylus is oriented at a different anglerelative to the plane of the input surface of the electronic device.

FIG. 5N depicts the stylus of FIG. 5K, particularly illustrating therelative position of the tip field intersection area and the ring fieldintersection area when the stylus is oriented at an angle that is nearlyparallel to the plane of the input surface of the electronic device.

FIG. 6A depicts a cross-section of a nosepiece of a stylus, specificallydepicting one example of a tip-field generator integrated within thenosepiece.

FIG. 6B depicts a cross-section of a nosepiece of a stylus, specificallydepicting another example of a tip-field generator integrated within thenosepiece.

FIG. 6C depicts a cross-section of a nosepiece of a stylus, specificallydepicting a tip-field generator and a ring-field generator integratedwithin the nosepiece.

FIG. 6D depicts the nosepiece of FIG. 6C without grounding signal lines.

FIG. 6E depicts the nosepiece of FIG. 6C without tip signal lines orring signal lines.

FIG. 6F depicts a cross-section of a nosepiece of a stylus, specificallydepicting another example of a tip-field generator integrated within thenosepiece.

FIG. 6G depicts a cross-section of a nosepiece of a stylus, specificallydepicting another example of a tip-field generator integrated within thenosepiece.

FIG. 7 depicts a cross-section of a nosepiece of a stylus, specificallyillustrating the nosepiece supported by a force-sensitive structure of acoordination engine disposed within the body of the stylus.

FIG. 8A depicts a plan view of a controller board set that may be foldedin order to be received in a thin form factor of a stylus.

FIG. 8B depicts a side view of the flexible circuit of FIG. 8A, viewedalong line F-F, specifically illustrating the placement of a two-axisstandoff configured to couple the flexible circuit, when folded, to achassis within the stylus.

FIG. 8C depicts a side view of the flexible circuit of FIG. 8A, viewedalong line F-F, specifically illustrating surface-mount standoffsconfigured to couple the flexible circuit, when folded, to a chassiswithin the stylus.

FIG. 9A depicts a power connector of a stylus and a blind cap forconcealing the power connector when not in use.

FIG. 9B depicts the power connector and blind cap of FIG. 9A, shown incross-section through line G-G, specifically showing a configuration ofmagnets that attract the blind cap to the power connector.

FIG. 9C depicts another example power connector and blind cap,specifically showing another magnetic configuration that attracts theblind cap to the power connector.

FIG. 9D depicts yet another example power connector and blind cap,specifically showing another magnetic configuration that attracts theblind cap to the power connector.

FIG. 10A depicts a cross-section of a power connector of a stylus and ablind cap for concealing the power connector when not in use,particularly showing a configuration of leaf springs within the blindcap that is configured to engage with detents of the power connector.

FIG. 10B depicts the cross-section of FIG. 10A, particularly showing theleaf springs of the blind cap engaged with the detents of the powerconnector.

FIG. 10C depicts a cross-section of a power connector and a blind cap,particularly showing an alternative configuration of leaf springs withinthe blind cap.

FIG. 10D depicts a blind cap for concealing a power connector of astylus, particularly showing a hoop spring configuration within theblind cap that is configured to engage with detents of the powerconnector.

FIG. 10E depicts a cross-section of the blind cap of FIG. 10D takenthrough line H-H.

FIG. 10F depicts the cross-section of FIG. 10E, specifically showing thehoop spring engaged with detents of the power connector.

FIG. 10G depicts another example cross-section of a blind capincorporating one or more hoop-springs that are configured to engagewith detents of a power connector.

FIG. 10H depicts yet another example cross-section of a blind capincorporating one or more hoop-springs that are configured to engagewith detents of a power connector.

FIG. 11A depicts a stylus incorporating the power connector coupled toan electronic device.

FIG. 11B depicts the stylus and electronic device of FIG. 11A,specifically illustrating flexibility of the power connector.

FIG. 11C depicts a stylus incorporating the power connector of FIG. 11Acoupled to a charging stand.

FIG. 11D depicts a stylus incorporating the power connector of FIG. 11Acoupled to a charging cable.

FIG. 11E depicts a stylus incorporating a power connector that isconfigured to electrically couple to an external surface of anelectronic device.

FIG. 11F depicts the stylus and electronic device of FIG. 11E in a matedconfiguration.

FIG. 12 is a flow chart depicting operations of a process of locatingand estimating the angular position of a stylus touching an inputsurface of an electronic device.

FIG. 13 is a flow chart depicting operations of a process of estimatinga force applied by a stylus to an input surface of an electronic device.

FIG. 14 is a flow chart depicting operations of a process ofmanufacturing a stylu8described herein.

FIG. 15 is a flow chart depicting operations of a process of exiting alow power mode of a stylus.

FIG. 16 is a flow chart depicting operations of a process of entering alow power mode of a stylus.

FIG. 17 is a flow chart depicting operations of a process of notifying auser to charge a stylus.

FIG. 18 is a flow chart depicting operations of a process of charging astylus with an electronic device.

FIG. 19 is a flow chart depicting operations of a process of notifying auser that a stylus is charged.

FIG. 20 is a flow chart depicting operations of a process of operatingan electronic device in either a touch input mode or a stylus inputmode.

FIG. 21 is a flow chart depicting operations of a process of operatingan electronic device in both a touch input mode and a stylus input mode.

FIG. 22 is a flow chart depicting operations of a process ofcompensating for tilt-induced offset when locating a stylus on an inputsurface.

FIG. 23 is a flow chart depicting operations of a process ofmanufacturing a blind cap incorporating a pressure vent.

FIG. 24 is a flow chart depicting operations of a process of operating auser input system in more than one mode.

The use of the same or similar reference numerals in different figuresindicates similar, related, or identical items.

The use of cross-hatching or shading in the accompanying figures isgenerally provided to clarify the boundaries between adjacent elementsand also to facilitate legibility of the figures. Accordingly, neitherthe presence nor the absence of cross-hatching or shading conveys orindicates any preference or requirement for particular materials,material properties, element proportions, element dimensions,commonalties of similarly illustrated elements, or any othercharacteristic, attribute, or property for any element illustrated inthe accompanying figures.

Additionally, it should be understood that the proportions anddimensions (either relative or absolute) of the various features andelements (and collections and groupings thereof) and the boundaries,separations, and positional relationships presented therebetween, areprovided in the accompanying figures merely to facilitate anunderstanding of the various embodiments described herein and,accordingly, may not necessarily be presented or illustrated to scale,and are not intended to indicate any preference or requirement for anillustrated embodiment to the exclusion of embodiments described withreference thereto.

DETAILED DESCRIPTION

Embodiments described herein generally reference a stylus (e.g., amarking tool, smart pen, smart brush, wand, chisel, user-manipulatedelectronic input device, hand-held input device, and the like) that isconfigured to provide input to an electronic device (e.g., tabletcomputer, laptop computer, desktop computer, and the like). The usermanipulates the orientation and position of the stylus relative to aninput surface of the electronic device to convey information to theelectronic device such as, but not limited to, writing, sketching,scrolling, gaming, selecting user interface elements, moving userinterface elements, and so on. In many embodiments, the input surface ofthe electronic device is a multi-touch display screen, but this is notrequired; in other embodiments, the input surface can be a non-displayinput surface such as a trackpad or drawing tablet. Collectively, thestylus and the electronic device are referred to herein as a “user inputsystem.”

The user input system described herein may be used to capture free-formuser input from the stylus. For example, the user can slide, move, draw,or drag a tip of the stylus across the input surface of the electronicdevice which, in response, may render a line using a display positionedbelow the input surface. In this example, the rendered line follows orcorresponds to the path of the stylus across the input surface. Thethickness of the rendered line may vary based at least in part on aforce or speed with which the user moves the stylus across the inputsurface. In other cases, the thickness of the rendered line may varybased, at least in part, on an angle of the stylus relative to the inputsurface, such as, but not limited to, the inclination of the stylusrelative to the plane of the input surface, a writing angle of thestylus relative to a horizontal writing line traversing the inputsurface, and so on. In other examples, the stylus and electronic devicemay be used together for any other suitable input purpose.

Broadly and generally, the user input system described herein determinesand/or estimates one or more outputs of the stylus (and/or changestherein over time as a scalar or vector quantity), to interpret theuser's manipulation thereof as input to the electronic device. Forexample, the user input system can estimate: the magnitude of forceapplied by a user's grip to the stylus (e.g., non-binary estimate ofmagnitude as a scalar or vector quantity); a magnitude (e.g., non-binaryestimate of magnitude as a scalar or vector quantity) of force appliedby the stylus to the input surface of the electronic device; thelocation at which or the area over which the tip of the stylus touchesthe input surface of the electronic device; a distance between alocation of the stylus tip and a user's palm, wrist, or other fingersalso in contact with the input surface; a polar angle of the stylusrelative to the plane of the input surface (e.g., inclination of thestylus); an azimuthal angle of the stylus relative to an axis of theinput surface; a vector or scalar representation of the angular positionof the stylus relative to the plane of the input surface;three-dimensional coordinates (e.g., spherical, Cartesian, and so on) ofone or more points along the length of the stylus relative to the inputsurface; and so on. In many embodiments, the user input system monitorssuch variables over time to estimate rates of change therein as eitherscalar or vector quantities (e.g., velocity, acceleration, and so on).

The operation of estimating or determining the two-dimensional positioncoordinates of the stylus as a point (or area) within or parallel to theplane of the input surface, whether such operation is performed by theelectronic device, performed by the stylus, and/or performed, at leastin part, as a result of cooperation therebetween (or with one or moreother electronic devices), is generally referred to herein as “locating”the stylus. In many embodiments, this operation involves estimatingCartesian coordinates of the stylus tip relative to an origin point ofplane of the input surface of the electronic device, such as the lowerleft-hand corner of the external surface of a cover glass disposed overa touch-sensitive display of the electronic device. In other examples,this operation involves estimating a two-dimensional area or region ofthe input surface that the tip of the stylus touches. The Cartesiancoordinates (and/or set of coordinates associated with an area) can berelative to an origin point defined by a plane parallel to, orassociated with, the input surface itself (e.g., a local Cartesiancoordinate system). In one example, the origin point can be in an upperright-hand corner of a rectangular input surface. The location of thestylus can be represented in any suitable manner or format, such as withvector or scalar quantities.

The operation of estimating the orientation of the stylus relative tothe plane of the input surface, whether such operation is performed bythe electronic device, performed by the stylus, and/or performed, atleast in part, as a result of cooperation therebetween (or with one ormore other electronic devices), is generally referred to herein asestimating the “angular position” of the stylus. In many embodiments,the operation of estimating the angular position of the stylus involvesestimating spherical coordinates that describe the orientation of thelongitudinal axis of the stylus relative to the plane of the inputsurface. In other cases, estimating the angular position of the stylusinvolves estimating the three-dimensional Cartesian coordinate(s) of oneor more reference points along the longitudinal axis of the stylus. Itmay be appreciated that any number of implementation-specific andsuitable methods for determining the angular position of the stylusrelative to the plane of the input surface can be employed in otherembodiments and, as with the location of the stylus, the angularposition of the stylus can be represented in any suitable manner orformat, such as with one or more vector or scalar quantities.

In some embodiments, a polar angle and an azimuthal angle of the stylusrelative to the plane and zenith of the input surface may be estimated.The polar angle may be calculated as the angle of the stylus relative toa vector normal to the plane of the input surface (e.g., zenith) and theazimuthal angle may be calculated as the angle of the stylus relative toa vector parallel to the plane of the input surface (e.g., an axis). Inthese examples, the location of the tip of the stylus on the inputsurface can be considered the origin of a local spherical coordinatesystem defining the angular position of the stylus.

Although the operations of locating and estimating the angular positionof the stylus are generally referenced herein with respect to alocally-defined Cartesian coordinate system and a locally-definedspherical coordinate system, one of skill in the art will appreciatethat such coordinate systems are not required for any particularembodiment, and other coordinate systems, or cooperation of multiplecoordinate systems, can be used in the performance of variouscalculations and operations such as described herein. In some examples,affine transformations or similar computations or translations may beperformed by either or both of the electronic device or stylus in orderto shift from one coordinate system to another.

As noted above, the electronic device and/or the stylus can beconfigured to estimate and/or monitor the location and angular positionof the stylus over time and compute differential or integral quantitiessuch as, but not limited to, acceleration, velocity, total forceapplied, path length, and so on. For example, the operation ofestimating the velocity and/or acceleration of the stylus relative tothe input surface as the stylus is moved across that surface, whethersuch operation is performed by the electronic device, performed by thestylus, and/or performed, at least in part, as a result of cooperationtherebetween (or with one or more other electronic devices) is generallyreferred to herein as estimating the “planar motion” of the stylus. Inmany embodiments, this operation involves estimating a relative movementof the stylus over time and, more particularly, a change in the locationof the stylus over time. A change in the location of the stylus over aparticular time period may be used to estimate the velocity of thestylus during that time period. Similarly, a change in the velocity ofthe stylus in a particular time period may be used to estimate theacceleration of the stylus during that time period.

The operation of estimating the angular velocity and/or acceleration ofthe stylus relative to the plane of the input surface as it is movedthereacross, whether performed by the electronic device, performed bythe stylus, and/or performed, at least in part, as a result ofcooperation therebetween, is generally referred to herein as estimatingthe “angular motion” of the stylus. In many embodiments, this operationinvolves estimating changes in the polar and azimuthal angle of thestylus over time. A change in the polar angle of the stylus in aparticular time period is the polar angular velocity of the stylusduring that time period. A change in the azimuthal angle of the stylusin a particular time period is the azimuthal angular velocity of thestylus during that time period. In these embodiments, changes in thepolar angular velocity or the azimuthal angular velocity in a particulartime period are referred to herein, generally, as the polar angularacceleration and azimuthal angular acceleration, respectively.

In many embodiments, the force applied by the stylus to the inputsurface can be estimated, measured, calculated or otherwise computedexactly or approximately. As used herein, the term “force” refers toforce estimates, determinations, and/or calculations, which maycorrespond to properties or characteristics such as pressure,deformation, stress, strain, force density, force-area relationships,thrust, torque, and other effects that include force or relatedquantities.

The operation of estimating the force applied by the stylus to the inputsurface, whether performed by the electronic device, performed by thestylus, and/or performed, at least in part, as a result of cooperationtherebetween (or with one or more other electronic devices), isgenerally referred to herein as estimating the “applied force.” Morebroadly, the operation involves estimating the magnitude of forceapplied by and between a tip of the stylus and the input surface,dependent or independent of the orientation or direction of that force.In many embodiments, the force applied by the tip of the stylus to theinput surface is estimated by the stylus itself. For example, aforce-sensitive structure within the stylus can estimate the appliedforce by resolving or measuring a “reaction force” experienced by thestylus when the stylus applies a force to the input surface. Thereaction force is equal to and opposite of the force applied by thestylus to the input surface, and thus a measurement of the reactionforce by the stylus corresponds to a measurement of the applied force tothe input surface.

In other cases, the electronic device can directly measure the appliedforce. In such an example, it may not be required for the stylus todetermine or estimate the reaction force.

In still further embodiments, both an applied force and a reaction forcecan be estimated and/or determined. For example, a user input system mayobtain an estimate of the applied force in addition to an estimation ofthe reaction force. The user input system may select and use one or bothof the two measurements or, in other cases, the user input system cancombine the two measurements in an appropriate manner (e.g., average).

These and other embodiments are discussed below with reference to FIGS.1A-24. However, those skilled in the art will readily appreciate thatthe detailed description given herein with respect to these figures isfor explanatory purposes only and should not be construed as limiting.The section headings which appear throughout the description areprovided for convenience and organizational purposes only and are notintended to restrict or limit the disclosure within any particularsection to the embodiments, modifications, alternatives, details,features, and/or characteristics described in that section.

User Input Systems Incorporating a Stylus

Generally and broadly, FIGS. 1A-1D reference a user input system 100including an electronic device 102 and a stylus 104. A user 106manipulates the orientation and position of the stylus 104 relative toan input surface 108 of the electronic device 102 in order to conveyinformation to the electronic device 102. The user input system 100 maybe configured to perform or coordinate multiple operations such as, butnot limited to, locating the stylus 104, estimating the angular positionof the stylus 104, estimating the magnitude of force by the stylus 104to the input surface 108, and so on.

The user input system 100 can perform these and other operations at thesame time or at different times. In one non-limiting example, theoperation of determining the location of the stylus 104 can be performedsimultaneously with the operation of determining the angular position ofthe stylus 104 while the operation of estimating the magnitude of forceby the stylus 104 to the input surface 108 is performed onlyperiodically and/or based on whether the electronic device 102 isconfigured to accept force input from the stylus given a particularoperational mode of the electronic device 102 (or the stylus 104) at aparticular time. It is with respect to these and other embodiments thatFIGS. 1A-1D are provided.

FIG. 1A depicts a user input system 100 including an electronic device102 and a stylus 104. A user 106 slides a tip of the stylus 104 acrossan input surface 108 of the electronic device 102 to interact with auser interface presented or rendered on a display of the electronicdevice 102 positioned below the input surface 108 or integrated with theinput surface 108.

In other cases, the electronic device 102 may not include a display. Forexample, the electronic device 102 is presented in FIGS. 1A-1D as atablet computing device as an example only; other electronic devices(with or without displays positioned below the input surface 108) areenvisioned. For example, the electronic device of the user input system100 can be implemented as a peripheral input device, a trackpad, adrawing tablet, and the like.

Initially, reference is made to certain physical and operationalcharacteristics of the stylus 104, for example as shown in FIGS. 1A-1B.The stylus 104 may take various forms to facilitate use and manipulationby the user 106. In the illustrated example, the stylus 104 has thegeneral form of a writing instrument such as a pen or a pencil. In theillustrated embodiment, the stylus 104 includes a cylindrical body withtwo ends. In this example, the two ends of the body are terminatedrespectively with a tapered tip and a rounded cap. Either or both of thetapered tip and rounded cap can be removable, affixed to the body, or anintegral part of the body. The user 106 slides the tapered tip of thestylus 104 across the input surface 108 to convey information to theelectronic device 102. The electronic device 102 can interpret theuser's manipulation of the stylus 104 in any implementation-specific andsuitable manner.

The cylindrical body of the stylus 104, or more generally, the “body” orthe “barrel” can be formed from any number of suitable materials. Thebarrel is identified in FIG. 1B as the barrel 104 a. The barrel 104 acan be formed from plastics, metals, ceramics, laminates, glass,sapphire, wood, leather, synthetic materials, or any other material orcombination of materials. The barrel 104 a can form an outer surface (orpartial outer surface) and protective case for one or more internalcomponents of the stylus 104. The barrel 104 a can be formed of one ormore components operably connected together, such as a front piece and aback piece or a top clamshell and a bottom clamshell. Alternatively, thebarrel 104 a can be formed of a single piece (e.g., uniform body orunibody). In many embodiments, the barrel 104 a is formed from adielectric material.

In some embodiments, the barrel 104 a may be configured, partially orentirely, as an optical signal diffuser to diffuse an infrared signal oranother optical signal such as the light emitted from a multi-colorlight-emitting diode. In other cases, the barrel 104 a may beconfigured, entirely or partially, as an antenna window, allowing forwireless communications and/or electric fields to pass therethrough.

The barrel 104 a can be formed from a material doped with an agentconfigured to provide the barrel 104 a with a selected color, hardness,elasticity, stiffness, reflectivity, refractive pattern, texture, and soon. In other examples, the doping agent can confer other properties tothe barrel 104 a including, but not necessarily limited to, electricalconductivity and/or insulating properties, magnetic and/or diamagneticproperties, chemical resistance and/or reactivity properties, infraredand/or ultraviolet light absorption and/or reflectivity properties,visible light absorption and/or reflectivity properties, antimicrobialand/or antiviral properties, oleophobic and/or hydrophobic properties,thermal absorption properties, pest repellant properties, colorfastand/or anti-fade properties, antistatic properties, liquid exposurereactivity properties, and so on.

The barrel 104 a can exhibit a constant or a variable diametercross-section; as illustrated, the cylindrical cross-section view of thebarrel 104 a maintains a substantially constant diameter from thetapered tip to the rounded cap. The tapered tip is identified in FIG. 1Bas the tip 104 b. The rounded cap is identified in FIG. 1B as the blindcap 104 c.

In other embodiments, the barrel 104 a can include a variablecross-section (e.g., a “profile” of the barrel 104 a can change acrossthe length of the barrel 104 a). In one example, the diameter of thebarrel 104 a may be smaller near the tip 104 b than at the blind cap 104c. In some examples, the diameter of the barrel 104 a may bulge outwardin the middle of the barrel 104 a, between the tip 104 b and the blindcap 104 c. In some cases, the profile of the barrel 104 a can follow amathematical function such as a bump function, a Gaussian function, or astep function. The barrel 104 a can include one or more grip features(not shown) such as embossments or impressions, closely-spaced channels,protrusions, projections and/or the like. In some cases, a grip featurecan be formed from a different material than the barrel 104 a; the gripfeature(s) may be formed from a polymer material exhibiting highfriction.

Although illustrated as a cylinder, the barrel 104 a need not take acylindrical shape in all embodiments. Accordingly, as used herein, theterm “diameter” refers to the linear distance that can connect twopoints of a two-dimensional shape, whether the shape is circular orotherwise. For example, the stylus 104 can include a barrel 104 a withan n-sided polygonal cross-section (e.g., a vesica piscis cross-section,a triangular cross-section, a square cross-section, a pentagonalcross-section, and so on) that either varies in diameter or is constantin diameter.

In some examples, a cross-section view of the barrel 104 a is axiallysymmetric, although this is not required; certain styluses in accordancewith embodiments described herein include a barrel 104 a with across-section that is reflectionally symmetric along one axis whilebeing reflectionally asymmetric along another. In still furtherexamples, the barrel 104 a of the stylus 104 can be formed into anergonomic shape, including grooves, indents, and/or protrusionsconfigured to enhance the comfort of the user 106. In some cases, thebarrel 104 a includes a tapered section that decreases in diameter,linearly or non-linearly, toward the tip 104 b.

In many cases, the diameter of the barrel 104 a at the interface of thebarrel 104 a and the tip 104 b may be substantially similar to thediameter of the tip 104 b at that location. In this manner, the externalsurfaces of the tapered top and the barrel 104 a form a substantiallycontinuous external surface of the stylus 104.

In some cases, the barrel 104 a can define one or more apertures inwhich one or more input/output components such as a button, a dial, aslide, a force pad, a touch pad, audio component, haptic component, andthe like may at least partially reside. The apertures (and,correspondingly, the input/output components associated therewith) canbe defined at a lower end of the barrel 104 a nearby the tip 104 b. Inthis manner, the input/output components may be conveniently locatednear where the user 106 may rest the user's forefinger on the barrel 104a when grasping the stylus 104.

As shown in FIG. 1B, an indicator 110 can be disposed in anotheraperture defined by the barrel 104 a. In one example, the indicator 110includes a variable-brightness single or multi-color light-emittingdiode that is illuminated to convey information to the user 106, such as(but not limited to) a current operational mode of the stylus 104, acurrent operational mode of the electronic device 102, and/or theremaining battery life of the stylus 104. In other examples, a status oran operational mode of a program or application operating on theelectronic device 102 is conveyed to the user 106 by the indicator 110.The indicator 110 can be illuminated in any number of suitable andimplementation-specific ways. The indicator 110 can be positioned behinda diffuser or a lens. In other examples, more than one indicator can beincluded.

The blind cap 104 c of the stylus 104, or more generally, the “cap,” maybe configured to provide a cosmetic end to the barrel 104 a of thestylus 104. In some cases, the blind cap 104 c can be formed integrallywith the barrel 104 a, although this is not required of all embodiments.For example, in some embodiments, the blind cap 104 c can be removable.In one such example, the blind cap 104 c can be configured to conceal adata and/or power connector 112 of the stylus 104. The data and/or powerconnector 112 that may be concealed by the blind cap 104 c can beconfigured to couple to a power and/or data port 114 of the electronicdevice 102 (and/or another electronic device) to facilitate rechargingof a battery contained within the stylus 104. In other cases, the dataand/or power connector 112 can be used to exchange data between thestylus 104 and the electronic device 102 via the power and/or data port114. The data and/or power connector 112 can be configured to beflexible so that when connected to the power and/or data port 114, thestylus 104 can resist and withstand certain forces that may otherwisedamage the stylus 104 and/or the electronic device 102.

Although the data and/or power connector 112 is illustrated as amulti-pin, reversible, and standardized data and/or power connector, itis appreciated that such a connector is not required. Particularly, insome embodiments a Lightning connector, Universal Serial Bus connector,Firewire connector, serial connector, Thunderbolt connector, headphoneconnector, or any other suitable connector can be used.

As illustrated, the data and/or power connector 112 may extend outwardlyfrom the end of the barrel 104 a. However, this may not be required ofall embodiments. For example, the data and/or power connector 112 may beimplemented as a series of electrical contacts disposed on a surface ofthe barrel 104 a. In one example, the series of electrical contacts aredisposed on a flat tip surface of the barrel 104 a (e.g., a circularendcap of a cylindrical shape). In this embodiment, the data and/orpower connector 112 can retract, either manually or automatically, intothe barrel 104 a when not in use. In some examples, the data and/orpower connector 112 can be connected to a push-push mechanism. In theseembodiments, the blind cap 104 c may not be required. In theseembodiments, the data and/or power connector 112 is a male connectorconfigured to mate with a female receptacle such as the power and/ordata port 114. In other cases, the data and/or power connector 112 canbe a female receptacle configured to mate with a male connector. Inthese embodiments, the blind cap 104 c can include an extension portionthat is configured to fit within the data and/or power connector 112.The extension portion can include one or more magnets to attract to oneor more portions of the data and/or power connector 112.

The data and/or power connector 112 can include one or more detents,collectively labeled as a detent 112 a, that can help facilitateretention of the data and/or power connector 112 within the power and/ordata port 114 of the electronic device 102. Additionally, the detent 112a can help facilitate retention of the blind cap 104 c, such asdescribed below with reference to FIGS. 9A-9D. In other embodiments,detents may not be required.

In some cases, the blind cap 104 c includes a clip (not shown) forattaching the stylus 104 to a user's pocket, or any other suitablestorage location. The blind cap 104 c can include a through-holeconfigured to couple to a lanyard or tether. The lanyard or tether mayalso be configured to couple to the electronic device 102.

The blind cap 104 c may be formed from any suitable material, such as,but not limited to, metal, plastic, glass, ceramic, sapphire, and thelike or combinations thereof. In many cases, the blind cap 104 c isformed from the same material as the barrel 104 a, although this is notrequired. In some embodiments, the blind cap 104 c may be configured,entirely or partially, as a signal diffuser to diffuse an infraredsignal or another optical signal, such as a multi-color light-emittingdiode. In other cases, the blind cap 104 c may be configured, entirelyor partially, as an antenna window, allowing for wireless communicationsand/or electric fields to pass therethrough.

In some examples, the blind cap 104 c can include one or more pressurevents, generally labeled as the pressure vent 116. The pressure vents116 can provide a pressure normalization path when the blind cap 104 cis applied over the data and/or power connector 112 of the stylus 104.In other cases, the pressure vent 116 can be configured to preventand/or mitigate the development of a pressure differential that may, insome cases, eject the blind cap 104 c from the barrel 104 a of thestylus 104. The pressure vent 116 can include a valve that regulatesand/or otherwise controls the airflow.

As illustrated, the blind cap 104 c terminates in a rounded end,although this is not required of all embodiments. In some embodiments,the blind cap 104 c terminates as a plane. In other embodiments, theblind cap 104 c terminates in another suitable shape.

The blind cap 104 c can exhibit a constant or a variable diametercross-section. In many embodiments, such as illustrated, thecross-section view of the blind cap 104 c matches that of the barrel 104a where the barrel 104 a and the blind cap 104 c interface.

In other embodiments, the blind cap 104 c can include a variablecross-section. In one example, the diameter of the blind cap 104 c maybe smaller near the end of the blind cap 104 c than at the portion ofthe blind cap 104 c configured to connect to the barrel 104 a. In someexamples, the diameter of the blind cap 104 c may resemble an eraser ofa pencil. In some cases, the profile of the blind cap 104 c can follow amathematical function such as a bump function, a Gaussian function, or astep function. The blind cap 104 c can include grip features, such asembossments or impressions, closely-spaced channels, protrusions,projections, and/or the like. In some cases, a grip feature can beformed from a different material than the blind cap 104 c; the grip maybe formed from a polymer material exhibiting high friction.

The blind cap 104 c can be configured to be removably attached to thebarrel 104 a. In one embodiment, the blind cap 104 c is threaded suchthat the blind cap 104 c screws into corresponding threads within thebarrel 104 a. In other cases, the blind cap 104 c includes one or moredetents and/or recesses that are configured to align with one or morecorresponding recesses and/or detents within the barrel 104 a and/or theconnector that the blind cap 104 c may conceal. In other cases, theblind cap 104 c is interference-fit with or snap-fit to the barrel 104a. In still further cases, the blind cap 104 c is magnetically attractedto a portion of the barrel 104 a and/or the connector that the blind cap104 c may conceal.

In some cases, the blind cap 104 c can be configured as an inputcomponent. For example, the stylus 104 may operate in a first mode whenthe blind cap 104 c is attached and a second mode when the blind cap 104c is removed. Similarly, the stylus 104 operates in a first mode whenthe blind cap 104 c is rotated to a first angle whereas the stylus 104operates in a second mode when the blind cap 104 c is rotated to asecond angle. The electronic device 102 can also be configured tooperate in a mode that is related to the angular position of the blindcap 104 c of the stylus 104. In other cases, the stylus 104 and/or theelectronic device 102 can monitor the angle of rotation of the blind cap104 c as a rotational input. In other cases, the blind cap 104 c can bemechanically coupled to a switch such that pressing the blind cap 104 cissues a command or an instruction to the stylus 104 and/or theelectronic device 102.

The tip 104 b of the stylus 104, or more generally the “tip” may beconfigured to contact the input surface 108 of the electronic device 102in order to facilitate interaction between the user 106 and theelectronic device 102. The tip 104 b may taper to a point, similar to apen, so that the user 106 may control the stylus 104 with precision in afamiliar form factor. In some examples, the tip 104 b may be blunt orrounded, as opposed to pointed, or may take the form of a rotatable orfixed ball.

In many embodiments, tip 104 b is formed from a softer material than theinput surface 108. For example, the tip 104 b can be formed from asilicone, a rubber, a fluoroelastomer, a plastic, a nylon, conductive ordielectric foam, or any other suitable material or combination ofmaterials. In this manner, drawing of the tip 104 b across the inputsurface 108 may not cause damage to the input surface 108 or layersapplied to the input surface 108 such as, but not limited to,anti-reflective coatings, oleophobic coatings, hydrophobic coatings,cosmetic coatings, ink layers, and the like.

As with the barrel 104 a, the tip 104 b can be formed from a materialdoped with an agent configured to provide the tip 104 b with a selectedcolor, hardness, elasticity, stiffness, reflectivity, refractivepattern, texture and so on. In other examples, the doping agent canconfer other properties to the tip 104 b including, but not necessarilylimited to, electrical conductivity and/or insulating properties,magnetic and/or diamagnetic properties, chemical resistance and/orreactivity properties, infrared and/or ultraviolet light absorptionand/or reflectivity properties, visible light absorption and/orreflectivity properties, antimicrobial and/or antiviral properties,oleophobic and/or hydrophobic properties, thermal absorption properties,pest repellant properties, colorfast and/or anti-fade properties,antistatic properties, liquid exposure reactivity properties, and so on.

In many cases, the tip 104 b is formed from the same material as thebarrel 104 a, although this is not required. In some embodiments, thetip 104 b may be configured, entirely or partially, as a signal diffuserto diffuse an infrared signal or another optical signal such as amulti-color light-emitting diode. In other cases, the tip 104 b may beconfigured, entirely or partially, as an antenna window, allowing forwireless communications and/or electric fields to pass therethrough.

The tip 104 b can have a diameter that linearly decreases. In manyembodiments, such as illustrated, the cross-section view of the tip 104b matches that of the barrel 104 a where the barrel 104 a and tip 104 binterface, linearly decreasing until a termination point. In otherexamples, the cross-section view of the tip 104 b may decrease and/orincrease before terminating at the termination point. In some cases, theprofile of the tip 104 b can follow a mathematical function, such as abump function, a Gaussian function, or a step function. The tip 104 bcan include grip features, such as embossments or impressions,closely-spaced channels, protrusions, projections and/or the like. Insome cases, a grip feature can be formed from a different material thanthe tip 104 b; the grip may be formed from a polymer material exhibitinghigh friction.

The tip 104 b can be configured to be removably attached to the barrel104 a. In one embodiment, the tip 104 b is threaded such that the tip104 b screws into corresponding threads within the barrel 104 a. Inother cases, the tip 104 b includes one or more detents and/or recessesthat are configured to align with one or more corresponding recessesand/or detents within the barrel 104 a. In other cases, the tip 104 b isinterference-fit or snap-fit to the barrel 104 a. In still furthercases, the tip 104 b is magnetically attracted to a portion of thebarrel 104 a.

Electronic Devices Configured to Receive Input from a Stylus

Next, returning to FIG. 1A, reference is made to certain physical andoperational characteristics of the electronic device 102 and itsinteroperation with the stylus 104 depicted in FIGS. 1A-1B.

In some embodiments, the electronic device 102 locates and estimates theangular position of the stylus 104 substantially in real time. Theelectronic device 102 can perform these operations with and/or withoutcommunications from the stylus 104.

In the illustrated embodiment, the electronic device 102 is depicted asa tablet computing device, although this form-factor is not required ofall embodiments (as noted above). For example, the electronic device 102can be any suitable device, such as a desktop computer, laptop computer,cellular phone, an industrial or commercial computing terminal, amedical device, a peripheral or integrated input device, a hand-held orbattery powered portable electronic device, a navigation device, awearable device, and so on. For simplicity of illustration, many of thecomponents of the electronic device 102 of FIG. 1A described below areeither not labeled in FIGS. 1A-1D or are not depicted in FIGS. 1A-1D.

The electronic device 102 includes an enclosure (e.g., a “housing”). Thehousing 102 a can form an outer surface (or partial outer surface) andprotective case for one or more internal components of the electronicdevice 102. In the illustrated embodiment, the housing 102 a is formedin a substantially rectangular shape, although this configuration is notrequired. The housing 102 a can be formed of one or more componentsoperably connected together, such as a front piece and a back piece or atop clamshell and a bottom clamshell. Alternatively, the housing 102 acan be formed of a single piece (e.g., uniform body or unibody).

The housing 102 a may be configured to enclose, support, and retain theinternal components of the electronic device 102. Components of theelectronic device 102 can include, but are not necessarily limited to,one or more of a processor, a memory, a power supply, one or moresensors, one or more communication interfaces, one or more dataconnectors, one or more power connectors, one or more input/outputdevices, such as a speaker, a rotary input device, a microphone, anon/off button, a mute button, a biometric sensor, a camera, a forceand/or touch sensitive trackpad, and so on.

The electronic device 102 can include a display 108 a. The display 108 amay be positioned below the input surface 108. In other examples, thedisplay 108 a is integrated with the input surface 108. The display 108a can be implemented with any suitable technology, including, but notlimited to, a multi-touch and/or multi-force sensing touchscreen thatuses liquid crystal display technology, light-emitting diode technology,organic light-emitting display technology, organic electroluminescencetechnology, electronic ink, or another type of display technology orcombination of display technology types.

In some embodiments, the communication interfaces of the electronicdevice 102 facilitate electronic communications between the electronicdevice 102 and the stylus. 104. For example, in one embodiment, theelectronic device 102 may be configured to communicate with the stylus104 via a low-energy Bluetooth communication interface or a Near-FieldCommunication interface. In other examples, the communication interfacesfacilitate electronic communications between the electronic device 102and an external communication network, device or platform.

The communication interfaces, whether between the electronic device 102and the stylus 104 or otherwise, can be implemented as wirelessinterfaces, Bluetooth interfaces, Near Field Communication interfaces,magnetic interfaces, universal serial bus interfaces, inductiveinterfaces, resonant interfaces, capacitive coupling interfaces, Wi-Fiinterfaces, TCP/IP interfaces, network communications interfaces,optical interfaces, acoustic interfaces, or any conventionalcommunication interfaces.

The electronic device 102 may provide information related to externallyconnected or communicating devices and/or software executing on suchdevices, messages, video, operating commands, and so forth (and mayreceive any of the foregoing from an external device), in addition tocommunications. As noted above, for simplicity of illustration, theelectronic device 102 is depicted in FIGS. 1A-1D without many of theseelements, each of which may be included partially, optionally, orentirely, within the housing 102 a of the electronic device 102.

As noted above, the electronic device 102 includes an input surface 108.The input surface 108 cooperates with the housing 102 a of theelectronic device 102 to form an external surface thereof. In somecases, a top surface of the input surface 108 can be flush with anexternal surface of the housing 102 a, although this is not required ofall embodiments. In some examples, the input surface 108 stands proud ofat least a portion of the housing 102 a.

In many examples, the input surface 108 is formed from glass or anothersuitable material, such as plastic, sapphire, metal, ceramic,ion-implanted glass, and so on. In some cases, the input surface 108 isa solid material, whereas in other cases, the input surface 108 isformed by laminating or adhering several materials together. In somecases, the input surface 108 is optically transparent, whereas inothers, the input surface 108 is opaque.

The input surface 108 can include one or more cosmetic or functionallayers disposed on an outer surface thereof. For example, ananti-reflective coating may be applied to an outer (or inner) surface ofthe input surface 108. In another example, an oleophobic coating isapplied to the input surface 108. In other examples, a tactile layer isapplied to the input surface 108. The tactile layer can be configured toexhibit a specific kinetic or static friction when the stylus 104 ismoved thereacross.

The electronic device 102 can also include a display positioned below,or integrated with, the input surface 108. The electronic device 102utilizes the display to render images to convey information to the user.The display can be configured to show text, colors, line drawings,photographs, animations, video, and the like.

The display can be adhered to, laminated with, or positioned to contacta bottom surface of the input surface 108. The display can include astack of multiple elements that facilitate the rendering of imagesincluding, for example, a transparent circuit layer, a color filterlayer, a polarizer layer, and other elements or layers. The display maybe implemented with any suitable display technology including, but notlimited to, liquid-crystal display technology, organic light-emittingdiode technology, electroluminescent technology, and the like. Thedisplay may also include other layers for improving its structural oroptical performance, including, for example, glass sheets, polymersheets, polarizer sheets, color masks, rigid or resilient frames, andthe like.

The electronic device 102 can also include a sensor layer positionedbelow, or integrated with, the input surface 108 and/or the display ofthe electronic device 102. The electronic device 102 utilizes the sensorlayer to, among other purposes, detect the presence and/or location ofthe stylus 104 on the input surface 108. In other examples, theelectronic device 102 utilizes the sensor layer to detect the presenceof another object on the input surface 108, such as a finger of theuser. In still further examples, the electronic device 102 utilizes thesensor layer to detect the force with which an object, such as thestylus 104, presses on the input surface 108.

The sensor layer can be optically transparent or opaque. If the sensorlayer of a particular embodiment is disposed within the display, thesensor layer may be optically transparent so as to not impact theclarity of the display. In another example, the sensor layer may bedisposed around the perimeter of the display, positioned below a bezelsurrounding the display. In this embodiment, the sensor layer need notbe optically transparent.

Locating the Stylus

Next, reference is made to the operation of locating the stylus 104 onthe input surface 108 of the electronic device 102, using the sensorlayer of the electronic device 102. The electronic device 102 can locatethe tip of stylus 104, and estimate the Cartesian coordinates thereof,in a number of suitable ways.

In typical embodiments, the stylus 104 is located as a result ofcooperation between the stylus 104 and the electronic device 102.Generally and broadly, the stylus 104 may generate an electric fieldhaving a small effective diameter. This field intersects the inputsurface when the stylus is placed on it. The electronic device 102detects the field and estimates the location of the stylus based on thelocation (and/or area) at which the field is detected. The field thatmay be generated by the stylus 104 is described in greater detail belowwith specific reference to FIGS. 5A-5M.

More specifically, as noted above, the electronic device 102 can includea sensor layer that may be configured to detect electric fieldsgenerated by the stylus 104. In one embodiment, a sensor layer includesa number of capacitance sensing nodes. The capacitive sensing nodes canbe located on or between any suitable layer on or within the displayand/or on or within the input surface 108.

In some examples, the capacitive sensing nodes may be formed, at leastin part, from an optically transparent conductor such as, but notlimited to: metal oxides such as indium-tin oxide and antimony-tinoxide; nanowire patterns formed from silver nanowire, carbon nanotubes,platinum nanowire, gold nanowire, and so on; thin deposits of metal; andthe like. The capacitive sensing nodes may be configured to operate in aself, mutual, or other capacitance mode, capacitively coupling to thestylus 104 and detecting signals and fields generated thereby.

In these embodiments, the stylus 104 may create asubstantially-spherical electric field to be generated from its tip.This field affects the mutual capacitance of each capacitive sensingnode nearby the tip. The electronic device 102 locates the stylus 104 onthe input surface 108 by monitoring each capacitive sensing node forthese capacitive changes and estimating the location at which suchchanges (if any) have occurred.

As used herein, the term “tip signal” generally refers to an electricalsignal applied by the stylus 104 to the tip 104 b. As used herein, theterm “tip field” generally refers to the electric field generated by thetip 104 b of the stylus 104 in response to the tip signal. As notedabove, the tip field may take any suitable shape, but in manyembodiments, the tip field takes a substantially spherical shape and maybe modeled as a point source monopole electric field. The area of theinput surface 108 (or a plane parallel to the input surface 108)intersected by the tip field is generally referred to herein as the “tipfield intersection area.”

The perimeter of the tip field intersection area may be defined as theboundary after which the power density (e.g., magnitude) of the tipfield received by the electronic device 102 is below a selectedthreshold. In one example, the circumference of the tip fieldintersection area is defined at the half-power point of the tip field(e.g., 3 dB point). In other words, in this example the tip fieldintersection area is defined as a portion of the input surface 108intersected by the tip field with a magnitude at least greater than thehalf of the power at which that field was generated. Example structureswhich may be configured to generate and/or emit the tip field aredescribed in detail below, in particular with reference to FIGS. 3A and5A-5N.

Because the tip field is generated from the tip of the stylus 104, thetip field intersection area shifts substantially only based on thelocation of the stylus 104; the tip field intersection area may not, intypical embodiments, shift in a substantial manner based on the angularposition of the stylus 104. Thus, in order to determine the location ofthe stylus 104, the electronic device determines the geometric center ofthe tip field intersection area. However, as may be appreciated, thesensor layer of the electronic device 102 may be disposed a distancebelow the outermost surface of the input surface 108. In these examples,the tip field intersection area may depend upon the angular position ofthe stylus 104 (e.g., foreshortening/parallax effects).

In other embodiments, the location of the stylus 104 can be determinedby the electronic device 102, the stylus 104, or a combination thereof,in another manner. For example, the electronic device 102 can determinea tip field perimeter shape, a location of a maximum of the tip field, alocation of a minimum of the tip field, and so on. In other words, itmay be appreciated that although certain techniques are describedherein, other suitable techniques may be employed by an electronicdevice 102 or stylus 104 to determine the location of the stylus.

In many cases, the same sensor layer can also be used to detect one ormore fingers of the user 106 while simultaneously detecting the tipfield. In these cases, the electronic device 102 can accept both touchinput and stylus input. In particular, the capacitive sensing nodes maybe operated in a touch input mode to detect a finger touch and operatedin a tool input mode to detect a stylus input. The two modes may beswitched at a rate that enables simultaneous or near simultaneousdetection of both finger touches (multi-touch or single touch) andstylus input.

Angular Position of the Stylus

Referring next to FIGS. 1B-1D, reference is made to the operation ofestimating the angular position of the stylus 104 with respect to theinput surface 108. In these embodiments, the stylus 104 may generate asecond electric field that is separate and offset from the tip field.The second electric field is coaxially aligned with the tip field, andboth fields are axially symmetric along the longitudinal axis of thestylus 104, thereby allowing the stylus 104 to be grip-agnostic.

In order to ensure that the tip field and the second electric field areaxially symmetric, many embodiments generate the second electric fieldwith an electrically-conductive ring or tube having a small diameter. Insome embodiments, the diameter of the electrically-conductive ring isapproximately equal to the width of the electrical conductor thatgenerates the tip field (e.g., within one millimeter). A signal lineresponsible for conveying the tip signal to the tip 104 b passes throughthe electrically-conductive ring. In this manner, the field generated bythe electrically-conductive ring can be axially symmetric; the field isnot affected by the presence of signal lines responsible for conveyingthe tip signal to the tip 104 b.

As used herein, the term “ring signal” generally refers to theelectrical signal applied by the stylus 104 to generate the secondelectric field. In many embodiments, the second electric field is also asubstantially spherical electric field due to the small diameter of thering-shaped electrical conductor. In other words, although the source ofthe field is a ring-shaped conductor and not a point source, the radiusof the conductor is small enough in comparison to the distanceseparating the conductor from the tip (and thus the input surface 108 ofthe electronic device 102) that the ring field appears to the electronicdevice 102 as having originated from a point-source monopole.

In some embodiments, the ring-shaped electrical conductor is a tube orcylinder. In these embodiments, the electric field generated may take acapsule shape (e.g., a cylinder capped with hemi-spherical ends). Inthese embodiments, the ring-shaped conductor has a longitudinal axisthat is aligned along the longitudinal axis of the stylus 104. In thismanner, one hemi-spherical end of the capsule-shaped electric fieldgenerated from the tube-shaped electrical conductor is oriented towardthe tip 104 b of the stylus 104.

As with the tip field, as used herein, the term “ring field” generallyrefers to an electric field generated by the stylus 104 in response tothe ring signal. The area of the input surface 108 (or a plane parallelto the input surface 108) intersected by the ring field is generallyreferred to herein as the “ring field intersection area.”

In other embodiments, the angular position of the stylus 104 can bedetermined by the electronic device 102, the stylus 104, or acombination thereof, in another manner. For example, the electronicdevice 102 can determine a ring field perimeter shape, a location of amaximum of the ring field, a location of a minimum of the ring field,and so on. In other words, it may be appreciated that although certaintechniques are described herein, other suitable techniques may beemployed by an electronic device 102 or stylus 104 to determine theangular position of the stylus.

Thus, generally and broadly, a stylus such as described herein (e.g.,the stylus 104) generates two different electric fields, the origins ofwhich are offset from one another by a certain distance. The electricfields are aligned with one another along the longitudinal axis of thestylus so that the fields are axially symmetric. The first fieldoriginates proximate to the tip of the stylus and is referred to as thetip field. The second field originates a small distance offset from thetip field and is referred to as the ring field. Both the tip field andthe ring field are substantially spherical (or hemispherical) in thedirection of the tip of the stylus. When in use, the tip field and thering field respectively intersect an input surface (e.g., the inputsurface 108) of an electronic device (e.g., the electronic device 102)over a tip field intersection area and a ring field intersection area.In many cases, the intersection areas may be substantially circular.

As with the tip field intersection area, the perimeter of the ring fieldintersection area may be defined as the boundary after which the powerdensity (e.g., magnitude) of the ring signal received by the electronicdevice 102 is below a selected threshold. In one example, thecircumference of the ring field intersection area is defined at thehalf-power point of the ring field (e.g., 3 dB point). In other words,in this example the ring field intersection area is defined as a portionof the input surface 108 intersected by the ring field with a magnitudeat least greater than half of the power at which that field wasgenerated. Example structures which may be configured to generate and/oremit the ring field are described in detail below, in particular withreference to FIGS. 3A and 5A-5N.

The tip signal and the ring signal can each have at least onealternating current component that, via capacitive coupling or anothersuitable sensing technique, is received by the sensor layer of theelectronic device. In many embodiments, the frequency of the tip signalis different from the frequency or modulation pattern of the ring signal(e.g., frequency multiplexing). In other cases, the tip signal and thering signal can be time-multiplexed.

However, unlike the tip field, the ring field intersection area mayshift based on the angular position of the stylus 104 specificallybecause the origin of the ring field (e.g., the ring-shaped electricalconductor) is separated from the tip 104 b. Thus, tilting the stylus 104in one direction or another causes the ring field intersection area tochange in area and/or location, while the tip field intersection arearemains substantially fixed.

In these embodiments, the relative positions of the tip fieldintersection area and the ring field intersection area can be used toestimate the polar angle and the azimuthal angle of the stylus 104. Moreparticularly, the farther apart the geometric centers of the tip fieldintersection area and the ring field intersection are from one another,the smaller the polar angle (e.g., the closer the stylus 104 is toparallel with the input surface 108) of the stylus 104 relative to theinput surface 108. Similarly, the angle of the vector defined betweenthe geometric centers of the tip field intersection area and the ringfield intersection area can be used to estimate the azimuthal angle ofthe stylus 104 relative to the input surface 108.

In another non-limiting phrasing, in many embodiments, the electronicdevice 102 uses the known spherical diameter of the tip and ring field,diameter of the ring field intersection area, and/or the distancebetween the tip and the ring in order to estimate a polar angle 118(defined between a vector normal to the plane of the input surface 108and a longitudinal axis 120 of the stylus 104, such as a zenith) and anazimuthal angle 122 (defined between the polar angle 118 and a referencevector within the plane of the input surface 108, such as an axis).

To facilitate an understanding of the relative relationship between thepolar angle 118 and the azimuthal angle 122, FIGS. 1C and 1D areprovided depicting additional views of the electronic device 102 and thestylus 104 as shown in FIG. 1A, omitting the hand of the user 106 forclarity. FIG. 1C depicts a top view of the electronic device 102 of FIG.1A, specifically illustrating the azimuthal angle 122 of the stylus 104relative to the plane of the input surface 108. Similarly, FIG. 1Ddepicts a bottom side view of the electronic device of 102, specificallyillustrating the polar angle 118 of the stylus 104 relative to the planeof the input surface of the electronic device.

Many embodiments are described herein with reference to a sensor layerof the electronic device 102 that may be configured to detect the tipsignal and the ring signal by monitoring mutual capacitance. However, itmay be appreciated that the electronic device 102 can be appropriatelyconfigured in any implementation-specific manner to detect both the ringfield and the tip field. For example, electronic devices can include asensor layer configured to monitor for changes in the self-capacitanceof one or more capacitive sensor nodes. In other examples, an electronicdevice can be configured to operate in both a self-capacitance mode anda mutual capacitance mode. In other embodiments, other sensingtechniques can be used to determine the location and relative positionof the tip field and the ring field.

As noted above, the sensor layer can also be used to detect one or morefingers of the user 106 while simultaneously detecting the ring field.In these cases, the electronic device 102 can accept both touch inputand stylus input.

Detection of Force Applied by the Stylus

Returning to FIG. 1B, reference is made to the operation of estimatingthe force applied F_(a) by the stylus 104 to the input surface 108. Aswith other embodiments described herein, the force applied by the stylus104 can be estimated, measured, approximated, or otherwise obtained in anumber of ways.

In some examples, the force is estimated by the electronic device 102.In other examples, the force is estimated by the stylus 104, after whichthe stylus 104 communicates the estimated force to the electronic device102 (e.g., via a wireless communication interface) as a vector or scalarquantity using any suitable encoded or not-encoded format. In stillfurther embodiments, a force estimate obtained by the electronic device102 and a force estimate obtained by the stylus 104 can be combined,averaged, or otherwise used together to estimate the magnitude of forceapplied by the stylus 104.

Initially, reference is made to embodiments in which the electronicdevice 102 estimates the force applied F_(a) by the stylus 104. In theseembodiments, the electronic device 102 can include one or morecomponents configured to estimate and/or approximate force applied tothe input surface 108. Upon estimating that the tip of the stylus 104 iscontacting the input surface 108, the electronic device 102 estimatesthe force applied F_(a) thereby. In these embodiments, the forceestimated by the electronic device 102 can be obtained as a force vectornormal to the input surface 108. In these cases, the electronic device102 may resolve the force vector (e.g., using the law of cosines) into avector component parallel to the longitudinal axis 120 and a componentparallel to the input surface 108 using the polar angle 118 and theazimuthal angle 122 (e.g., computed in accordance with techniquespresented above). The electronic device 102 can interpret the magnitudesor directions of either or both of the component parallel to the inputsurface 108 and the component parallel to the angular position of thestylus 104 as a user input.

Next, reference is made to embodiments in which the stylus 104 estimatesthe force applied F_(a) to the input surface 108. In these examples, thestylus 104 estimates the reaction force F_(r) experienced by the stylusitself; the reaction force F_(r) is equal in magnitude and opposite insign of the force applied F_(a) by the stylus 104 to the input surface108.

In one embodiment, the tip 104 b of the stylus 104 is formed, at leastpartially, from a force-sensitive material, such as piezoelectricmaterial. A circuit within the stylus 104 estimates an electricalproperty of the force-sensitive material in order to estimate whetherthe tip 104 b of the stylus 104 is experiencing a reaction force F_(r).After obtaining an estimate of the reaction force F_(r), the stylus 104can communicate the force applied F_(a) by the tip 104 b to theelectronic device 102.

In another embodiment, a force-sensitive structure can be integratedbetween the tip 104 b and the barrel 104 a of the stylus 104. Theforce-sensitive structure can include a number of independent forcesensors, disposed within a gasket seal positioned between the tip 104 band the barrel 104 a. A circuit within the stylus 104 estimates anelectrical property of the gasket seal in order to estimate whether thetip 104 b is experiencing a reaction force. Thereafter, the stylus 104can communicate the force applied F_(a) by the tip 104 b to theelectronic device 102.

In another embodiment, a force-sensitive structure can be integratedwithin the barrel 104 a of the stylus 104. The force-sensitive structurecan include a number of independent strain or force-responsive elementsdisposed at various locations along the barrel 104 a. Upon detecting oneor more forces (e.g., from one or more of the fingers of the user 106),the stylus 104 can resolve and/or combine such forces into a singlevector parallel to the longitudinal axis 120. More particularly, inthese embodiments, the stylus 104 designates that the tip 104 b is thefulcrum of a second class lever. In this manner, if the various forcesdetected by the force-sensitive structure at various locations acrossthe barrel 104 a of the stylus 104 sum to zero, the stylus 104 canestimate that the tip 104 b of the stylus 104 is not in contact with theinput surface 108. Conversely, if the various forces detected by theforce-sensitive structure at various locations across the body of thestylus 104 do not sum to zero, the stylus 104 can infer that remainingforce must be applied through the tip 104 b to the input surface 108.Thereafter, the stylus 104 can communicate the force applied F_(a) bythe tip 104 b to the electronic device 102.

In other embodiments, the tip 104 b of the stylus 104 can be movable,generally along the longitudinal axis 120. In this manner, when the tip104 b of the stylus 104 touches the input surface 108 (or any othersurface), and applies a force, it withdraws at least partially into thebarrel 104 a of the stylus 104 as a direct result of the reaction forceF_(r). The amount of withdrawal can vary from embodiment to embodiment.In one non-limiting example, the tip 104 b can withdraw into the body ofthe stylus 104 by less than 1.0 mm. In other embodiments, the tip 104 bcan withdraw into the body of the stylus 104 by less than 0.1 mm. Instill further embodiments, the tip 104 b can withdraw by a different(e.g., greater or less) amount.

In these examples, a force-sensitive structure within the body of thestylus 104 may be coupled to the tip 104 b. The force-sensitivestructure can serve several purposes. For example, the force-sensitivestructure can provide support to the tip 104 b. In another example, theforce-sensitive structure can guide the withdrawal of the tip 104 b intothe barrel 104 a. In another example the force-sensitive structure canrestore the tip 104 b of the stylus 104 to a neutral position when forceF_(a) is no longer applied thereby.

In one embodiment, the force-sensitive structure includes a basingmechanism that biases the tip 104 b of the stylus 104 outwardly,providing resistance against the withdrawal of the tip 104 b into thebody of the stylus 104. In some cases, the biasing mechanism is ahelical spring or a leaf spring.

The force-sensitive structure can be formed, at least in part, frommetal. The force-sensitive structure can include a lateral bed with twocantilevered legs extending from each end of the lateral bed. Thecantilevered legs can be formed from the same material as the lateralbed. In some embodiments, the lateral bed and the cantilevered legs areformed as a single, integral part. In other examples, the cantileveredlegs are attached to the lateral bed via adhesive, welding, or any othersuitable method.

Each of the cantilevered legs can be fixed relative to an internal frameof the stylus 104, suspending the lateral bed of the force-sensitivestructure within the body of the stylus 104. As noted above, the tip 104b of the stylus 104 may be mechanically coupled to a portion of theforce-sensitive structure. For example, the tip 104 b can be coupled toat least one of the cantilevered legs and/or the lateral bed. In thismanner, when the tip 104 b of the stylus 104 moves inwardly with respectto the body (e.g., in response to the tip touching the input surface 108and applying a force), the cantilevered legs may deflect in apredictable manner. The deflection of one or both of the cantileveredlegs may be measured using a strain sensor or other sensing apparatuswhich, in turn, can be used to estimate the force applied by the stylus104.

Upon removing the stylus 104 from the input surface 108, one or both ofthe cantilevered legs of the force-sensitive structure may exhibit arestoring force that returns the tip of the stylus 104 to its neutralposition.

In many embodiments, the cantilevered legs are substantially orthogonalto the lateral bed when in a neutral position (e.g., when the tip is notapplying a force and the stylus 100 is in the ready state). In othercases, the cantilevered legs extend from the lateral bed at an obliqueangle. In some cases, both cantilevered legs connect to the same side ofthe lateral bed; a profile of the force-sensitive structure takes awidened U-shape. In other cases, the cantilevered legs connect toopposite sides of the lateral bed; a profile of the force-sensitivestructure takes an elongated S-shape or Z-shape.

In these embodiments, the strain sensor (or other sensing apparatus) mayexhibit an electrically-measurable property that changes as a functionof the magnitude of force applied. In one example, a strain sensor maybe coupled to a cantilevered leg of the force-sensitive structure. Thestrain sensor can be coupled to an electrical circuit within the stylus104. The electrical circuit can be configured to monitor one or moreelectrical properties (e.g., resistance, capacitance, accumulatedcharge, inductance, and so on) of the strain sensor for changes.

When the tip 104 b of the stylus 104 applies a force to the inputsurface 108, the tip 104 b moves inwardly with respect to the body ofthe stylus 104, which in turn causes at least one of the cantileveredlegs of the force-sensitive structure to deflect, which in turn causesone or more electrical properties of the strain sensor to change. Theelectrical circuit then quantifies these changes and, in turn, reportsthat a force is estimated. Thereafter, the stylus 104 can communicatethe force applied by the tip 104 b to the electronic device 102.

The foregoing description of the embodiments depicted in FIGS. 1A-1D,and various alternatives and variations, are presented, generally, forpurposes of explanation, and to facilitate a thorough understanding ofthe detailed embodiments presented below. However, it will be apparentto one skilled in the art that some of the specific details presentedherein may not be required in order to practice a particular describedembodiment, or an equivalent thereof. Thus, the foregoing and followingdescriptions of specific embodiments are presented for the limitedpurposes of illustration and description. These descriptions are nottargeted to be exhaustive or to limit the disclosure to the preciseforms recited herein. To the contrary, it will be apparent to one ofordinary skill in the art that many modifications and variations arepossible in view of the above teachings. Particularly, it may beunderstood that the user input system depicted in FIGS. 1A-1D includingan electronic device and a stylus can be implemented in a number ofsuitable and implementation-specific ways.

However, broadly and generally, the electronic device determines and/orestimates characteristics of the stylus and/or changes therein overtime, to interpret the user's manipulation thereof as input. Theelectronic device obtains, through its own estimate or by communicationwith the stylus, the location of the stylus, the angular position of thestylus, the force applied by the stylus to the electronic device, thevelocity of the stylus, the acceleration of the stylus, the polarangular velocity or acceleration of the stylus, the azimuthal angularvelocity or acceleration of the stylus, and so on. Any of theseoperations, or portions of these operations, may be performed by theelectronic device, by the stylus, and/or performed, at least in part, asa result of cooperation and communication therebetween.

General Operation of a User Input System

FIGS. 2A-2F generally depict simplified system diagrams of a user inputsystem 200 including an electronic device 202 and a stylus 204, andvarious sub-portions thereof. For simplicity of illustration, many ofthese simplified system diagrams may be presented without signal and/orinterconnection paths between system elements that may be required ordesirable for a particular embodiment. Accordingly, it may be understoodthat one or more of the various system elements depicted in thesimplified block diagrams of FIGS. 2A-2F may be electrically orcommunicably configured, in an implementation-specific and appropriatemanner, to be in communication with any other appropriate systemelement. Particularly, one or more of the various system elements can beconfigured to exchange data, power, analog or digital signals, or thelike, via one or more circuit traces, jumpers, cables, wired or wirelesscommunication interfaces, data buses, and so on with any otherappropriate system element. Similarly, it may be understood that one ormore of the various system elements depicted in the simplified blockdiagrams of FIGS. 2A-2F may be mechanically configured, in animplementation-specific and appropriate manner, to be coupled to (or tobe mechanically isolated from) any other appropriate system element.

Accordingly, the absence or presence of a signal path and/or aninterconnection path between various system elements of the simplifiedsystem diagrams depicted in FIGS. 2A-2F is not to be construed as apreference or requirement for the presence or absence of any particularelectrical or mechanical relationship between the various systemelements.

Initially, reference is made to certain operational components of theuser input system 200 depicted in FIG. 2A. As with other embodimentsdescribed herein, the user input system 200 includes an electronicdevice 202 and a stylus 204. The electronic device 202 can beimplemented as any suitable electronic device including, but not limitedto: a desktop computer, laptop computer, cellular phone, an industrialor commercial computing terminal, a medical device, a peripheral orintegrated input device, a hand-held or battery powered portableelectronic device, a navigation device, a wearable device, and so on.The user input system 200 of FIG. 2A may correspond to the user inputsystem 100 discussed above with respect to FIGS. 1A-1D.

The stylus 204 can be formed to take substantially any shape that can bemanipulated with one hand of a user. For example, in many embodiments,the stylus 204 takes the shape of a stylus, a pen, a smart brush, awand, a chisel, and so on.

As noted with respect to other embodiments described herein, a usermanipulates the orientation and position of the stylus 204 relative toan input surface of the electronic device 202 to convey information tothe electronic device 202. In many embodiments, the input surface of theelectronic device 202 is a display screen, but this is not required; inother embodiments, the input surface can be a non-display input surface,such as a trackpad or drawing tablet.

General Operation of a Stylus of a User Input System

Next, reference is made to certain operational components of an examplestylus 204, such as depicted in FIG. 2B. The stylus 204 can includeseveral subsystems that cooperate to perform, coordinate, or monitor oneor more operations or functions of the stylus 204 or, more generally,the user input system 200. Particularly, as shown in FIG. 2B, the stylus204 includes a coordination engine 206, a processing unit 208, a powersubsystem 210, a wireless interface 212, and a power connector 214.

Generally and broadly, the coordination engine 206 of the stylus 204 maybe tasked with generating the tip field and the ring field as describedabove. These fields facilitate discovery of the coordinates, bothCartesian and spherical, of the stylus 204 by the electronic device 202.In some embodiments, the coordination engine 206 may also be tasked withmeasuring the force applied by the stylus 204, such as the reactionforce F_(r) described with respect to FIGS. 1A-1D.

In many embodiments, one or more components of the coordination engine206 can include or can be communicably coupled to circuitry and/or logiccomponents, such as a processor and a memory. The circuitry can controlor coordinate some or all of the operations of the coordination engine206 including, but not limited to: communicating with and/or transactingdata with other subsystems of the stylus 204; receiving parameters usedto generate the tip signal and the ring signal; conveying the tip signaland the ring signal to a tip-field generator and ring-field generatorrespectively; receiving the tip signal and the ring signal from anothersubsystem of the stylus 204; measuring and/or obtaining the output ofone or more analog or digital sensors, such as a strain sensor oraccelerometer; and so on. The coordination engine 206 is described indetail below with reference to FIG. 2D.

The processor of the coordination engine 206 can be implemented as anyelectronic device capable of processing, receiving, or transmitting dataor instructions. For example, the processor can be a microprocessor, acentral processing unit, an application-specific integrated circuit, afield-programmable gate array, a digital signal processor, an analogcircuit, a digital circuit, or combination of such devices. Theprocessor may be a single-thread or multi-thread processor. Theprocessor may be a single-core or multi-core processor.

Accordingly, as described herein, the phrase “processing unit” or, moregenerally, “processor” refers to a hardware-implemented data processingdevice or circuit physically structured to execute specifictransformations of data including data operations represented as codeand/or instructions included in a program that can be stored within andaccessed from a memory. The term is meant to encompass a singleprocessor or processing unit, multiple processors, multiple processingunits, analog or digital circuits, or other suitably configuredcomputing element or combination of elements.

The coordination engine 206 may be coupled to the processing unit 208and may be configured to provide the tip signal and ring signal to thecoordination engine 206. The processing unit 208 may also be configuredto facilitate communication with the electronic device 202, for example,via the wireless interface 212. The processing unit 208 is described indetail below with reference to FIG. 2E.

The processing unit 208, in many embodiments, can include or can becommunicably coupled to circuitry and/or logic components, such as aprocessor and a memory. The circuitry of the processing unit 208 canperform, coordinate, and/or monitor one or more of the functions oroperations of the processing unit 208 including, but not limited to:communicating with and/or transacting data with other subsystems of thestylus 204; communicating with and/or transacting data with theelectronic device 202; generating the tip signal and/or ring signal;measuring and/or obtaining the output of one or more analog or digitalsensors such as a strain sensor or accelerometer; changing a power stateof the stylus 204 from a normal power state to a standby power state ora low power state; modulating information and/or data onto either orboth the tip signal and ring signal; and so on.

The stylus 204 may be powered by an internal battery. The powersubsystem 210 may include one or more rechargeable batteries and a powercontroller. The power controller of the power subsystem 210 may beconfigured to facilitate rapid charging of the batteries when the powerconnector 214 is coupled to a power source. In some cases, the powersource to which the power connector 214 may be configured to connect tois a data and/or power port of the electronic device 202. In othercases, the power connector 214 includes one or more magnets that areconfigured to attract to a surface or channel of an electronic device.

The power controller of the power subsystem 210, in many embodiments,can include or can be communicably coupled to circuitry and/or logiccomponents, such as a processor and a memory. The circuitry of the powercontroller can perform, coordinate, and/or monitor one or more of thefunctions or operations of the power subsystem 210 including, but notlimited to: communicating with and/or transacting data with theelectronic device 202; controlling a charging rate of a battery;estimating and reporting a capacity of a battery at a particular time;reporting that a capacity of a battery has dropped below a minimumthreshold; reporting that a battery is charged; and so on. The powersubsystem 210 is described in detail below with reference to FIG. 2F.

It will be apparent to one skilled in the art that some of the specificdetails presented above with respect to the stylus 204 may not berequired in order to practice a particular described embodiment, or anequivalent thereof. Similarly, other styluses may include a greaternumber of subsystems, modules, components, and the like. Some submodulesmay be implemented as software or firmware when appropriate.Accordingly, it is appreciated that the description presented above isnot meant to be exhaustive or to limit the disclosure to the preciseforms recited herein. To the contrary, it will be apparent to one ofordinary skill in the art that many modifications and variations arepossible in view of the above teachings.

General Operation of an Electronic Device of a User Input System

Next, reference is made to FIG. 2C in which various subsystems of anexample electronic device 202 are shown. As with the stylus 204 depictedin FIG. 2B, the electronic device 202 can include several subsystemsthat cooperate to perform, coordinate, or monitor one or more operationsor functions of the electronic device 202 or, more generally, the userinput system 200. The electronic device 202 includes an input surface218, a coordination engine 220, a processing unit 222, a power subsystem224, a wireless interface 226, a power connector 228, and a display 230.

The coordination engine 220, in many embodiments, can include or can becommunicably coupled to circuitry and/or logic components, such as aprocessor and a memory. The circuitry of the coordination engine 220 canperform, coordinate, and/or monitor one or more of the functions oroperations of the coordination engine 220 including, but not limited to:communicating with and/or transacting data with other subsystems of theelectronic device 202; communicating with and/or transacting data withthe stylus 204; measuring and/or obtaining the output of one or moreanalog or digital sensors such as a touch sensor; measuring and/orobtaining the output of one or more sensor nodes of an array of sensornodes, such as an array of capacitive sensing nodes; receiving andlocating a tip signal and ring signal from the stylus 204; locating thestylus 204 based on the location of the tip signal intersection area andthe ring signal intersection area; and so on.

The coordination engine 220 of the electronic device 202 includes or isotherwise communicably coupled to a sensor layer positioned below, orintegrated with, the input surface 218. The coordination engine 220utilizes the sensor layer to locate the stylus 204 on the input surface218 and to estimate the angular position of the stylus 204 relative tothe plane of the input surface 218 using techniques described herein.

In one embodiment, the sensor layer of the coordination engine 220 ofthe electronic device 202 is a grid of capacitive sensing nodes arrangedas columns and rows. More specifically, an array of column traces isdisposed to be perpendicular to an array of row traces. A dielectricmaterial, such as a substrate, separates the column traces from the rowtraces such that at least one capacitive sensing node is formed at each“overlap” point where one column trace crosses over or below one rowtrace. Some embodiments dispose column traces and row traces on oppositesides of a substrate whereas others dispose column traces and row traceson the same side of a substrate. Some embodiments may only include rowtraces, whereas other may only include column traces. The sensor layercan be separate from other layers of the electronic device, or thesensor layer can be disposed directly on another layer such as, but notlimited to: a display stack layer; a force sensor layer; a digitizerlayer; a polarizer layer; a battery layer; a structural or cosmetichousing layer; and so on.

The sensor layer can be operated in a number of modes. If operated in amutual capacitance mode, a column trace and a row trace form a singlecapacitive sensing node at each overlap point (e.g., “vertical” mutualcapacitance). If operated in a self-capacitance mode, a column trace anda row trace form two (vertically aligned) capacitive sensing nodes ateach overlap point. In another embodiment, if operated in a mutualcapacitance mode, adjacent column traces and/or adjacent row traces caneach form single capacitive sensing nodes (e.g., “horizontal” mutualcapacitance.

In many embodiments, the sensor layer can operate in multiple modessimultaneously. In other embodiments, the sensor layer may rapidly shiftfrom one mode to another. In still further embodiments, the sensor layercan use a first mode to detect the presence or proximity of an object(e.g., a stylus, a user's finger, and so on) and then use a second modeto obtain an estimation of that object. For example, the sensor layermay operate in a self-capacitance mode until an object is detectednearby the input surface, after which the sensor layer transitions intoa mutual capacitance mode (either or both vertical or horizontal). Inother cases, capacitive sensing nodes can be disposed in anotherimplementation-specific and suitable manner.

Independent of the configuration of the sensor layer, the capacitivesensing nodes included therein may be configured to detect the presenceand absence of the tip field, the ring field, and/or the touch of auser's finger. The sensor layer can be optically transparent, althoughthis may not be required for all embodiments.

As noted above, the sensor layer can detect the presence of the tipfield, the presence of the ring field, and/or the touch of a user'sfinger by monitoring for changes in capacitance (e.g., mutualcapacitance or self-capacitance) exhibited at each of the capacitivesensing nodes. In many cases, the coordination engine 220 may beconfigured to detect the tip signal and the ring signal received throughthe sensor layer from the stylus 204 via capacitive coupling.

In some cases, the coordination engine 220 may be configured todemodulate, decode, or otherwise filter one or more raw signals receivedfrom the sensor layer in order to obtain the tip signal, the ringsignal, and/or data that may be modulated therewith. The operation ofobtaining the tip signal and the ring signal, as performed by thecoordination engine 220 (or another component communicably coupled tothe sensor layer or to the coordination engine 220), can be accomplishedin a number of implementation-specific ways, suitable for any number ofembodiments described herein or reasonable equivalents thereof.

In other embodiments, the sensor layer can be configured to operate inboth a self-capacitance mode and a mutual capacitance mode. In thesecases, the coordination engine 220 can monitor for changes inself-capacitance of one or more portions of each capacitive sensing nodein order to detect the tip field and/or ring field (and,correspondingly, obtain the tip signal and the ring signal), whilemonitoring for changes in mutual capacitance to detect the touch (ormore than one touch) of a user. In still further examples, the sensorlayer can be configured to operate in a self-capacitance modeexclusively.

The coordination engine 220 performs (or assists with the performanceof) the operation of locating and/or estimating the angular position ofthe stylus 204 on the input surface 218 employing techniques describedherein once the tip signal and the ring signal are obtained by thecoordination engine 220, and the tip field intersection area and thering field intersection area are determined. The coordination engine 220can forward such information to the processing unit 222 for furtherprocessing and interpretation once the location of the stylus 204 andthe angular position of the stylus 204 are estimated.

In many embodiments, the coordination engine 220 may be used to obtainestimations of the location of the stylus 204 within certain statisticalbounds. For example, the coordination engine 220 may be configured toestimate the location of the stylus 204 on the input surface 218 withinan error of 100 micrometers. In other embodiments, the coordinationengine 220 can be configured to estimate the location of the stylus 204on the input surface 218 within 50 micrometers. In still furtherembodiments, the coordination engine 220 can be configured to estimatethe location of the stylus 204 within 10 micrometers or less.

One may appreciate that the accuracy and/or precision of the operationof locating the stylus 204 by the coordination engine 220 may differfrom embodiment to embodiment. In some cases, the accuracy and/orprecision of the operation may be substantially fixed, whereas in othercases, the accuracy and/or precision of the operation may be variabledepending upon, among other variables: a user setting, a userpreference, a speed of the stylus; an acceleration of the stylus; asetting of a program operating on the electronic device; a setting ofthe electronic device; an operational mode of the electronic device; apower state of the electronic device; a power state of the stylus; andso on.

The coordination engine 220 may also be configured to obtain estimationsof the angular position of the stylus 204 within certain statisticalbounds. For example, the coordination engine 220 may be configured toestimate the angular position of the stylus 204 relative to the plane ofthe input surface 218 within an error of 0.2 radians (e.g.,approximately 11.5 degrees). In other embodiments, the coordinationengine 220 can be configured to estimate the angular position of thestylus 204 on the input surface 218 within 0.1 radians (e.g.,approximately 5 degrees). In still further embodiments, the coordinationengine 220 can be configured to estimate the angular position of thestylus 204 within 0.05 radians (e.g., approximately 3 degrees).

The accuracy and/or precision of the operation of estimating the angularposition of the stylus 204 by the coordination engine 220 may differfrom embodiment to embodiment. In some cases, the accuracy and/orprecision of the operation may be substantially fixed, whereas in othercases, the accuracy and/or precision of the operation may be variabledepending upon, among other variables: a user setting, a userpreference, a speed of the stylus; an acceleration of the stylus; asetting of a program operating on the electronic device; a setting ofthe electronic device; an operational mode of the electronic device; apower state of the electronic device; a power state of the stylus; andso on.

As noted above, the tip signal and/or the ring signal can includecertain information and/or data that may be configured to identify thestylus 204 to the electronic device 202. Such information is generallyreferred to herein as “stylus identity” information. This informationand/or data may be received by the sensor layer and interpreted,decoded, and/or demodulated by the coordination engine 220.

For example, the coordination engine 220 can forward stylus identityinformation (if detected and/or recoverable) to the processing unit 222.If stylus identity information is not recoverable from the tip signaland/or the ring signal, the coordination engine 220 can optionallyindicate to the processing unit 222 that stylus identity information isnot available. The electronic device 202 can utilize the stylus identityinformation (or an absence thereof) in any suitable manner including,but not limited to: accepting or rejecting input from a particularstylus; accepting input from multiple styluses; permitting or denyingaccess to a particular functionality of the electronic device; applyinga particular stylus profile; restoring one or more settings of theelectronic device; notifying a third party that the stylus is in use;and so on.

The processing unit 222 can use stylus identity information to receiveinput from more than one stylus at the same time. Particularly, thecoordination engine 220 can be configured to convey to the processingunit 222 the location and/or angular position of each of severalstyluses detected by the coordination engine 220. In other cases, thecoordination engine 220 can also convey to the processing unit 222information related to the relative location and/or relative angularposition of the several styluses detected by the coordination engine220. For example, the coordination engine 220 can inform the processingunit 222 that a first detected stylus is positioned 3 centimeters awayfrom a second detected stylus.

In other cases, and as noted with respect to other embodiments describedherein, the tip signal and/or the ring signal can also include certaininformation and/or data that serve to identify a particular user to theelectronic device 202. Such information is generally referred to hereinas “user identity” information.

The coordination engine 220 can forward user identity information (ifdetected and/or recoverable) to the processing unit 222. If useridentity information is not recoverable from the tip signal and/or thering signal, the coordination engine 220 can optionally indicate to theprocessing unit 222 that user identity information is not available. Theprocessing unit 222 can utilize the user identity information (or anabsence thereof) in any suitable manner including, but not limited to:accepting or rejecting input from a particular user; permitting ordenying access to a particular functionality of the electronic device;greeting a particular user; applying a particular user profile;restoring settings of the electronic device; locking the electronicdevice, thereby preventing access to any feature of the electronicdevice; notifying a third party that the user is identified or notidentified; and so on. The processing unit 222 can use user identityinformation to receive input from more than one user at the same time.

In still further other cases, the tip signal and/or the ring signal caninclude certain information and/or data that may be configured toidentify a setting or preference of the user or the stylus 104 to theelectronic device 202. Such information is generally referred to hereinas “stylus setting” information.

The coordination engine 220 can forward stylus setting information (ifdetected and/or recoverable) to the processing unit 222. If stylussetting information is not recoverable from the tip signal and/or thering signal, the coordination engine 220 can optionally indicate to theprocessing unit 222 that stylus setting information is not available.The electronic device 202 can utilize the stylus setting information (oran absence thereof) in any suitable manner including, but not limitedto: applying a setting to the electronic device; applying a setting to aprogram operating on the electronic device; changing a line thickness,color, pattern, and so on of a line rendered by a graphics program ofthe electronic device; changing a setting of a video game operating onthe electronic device; and so on.

Thus, generally and broadly, the coordination engine 220 facilitatesdistinction between many types of input that can all be used, separatelyor cooperatively, by the electronic device 202 in many differentimplementation-specific ways. For example, the electronic device 202 canuse any of the following as input: location of one or more styluses;polar angle of one or more styluses; azimuthal angle of one or morestyluses; angular or planar velocity or acceleration of one or morestyluses; gesture paths of one or more styluses; relative locationand/or angular position of one or more styluses; touch input provided bya user; multi-touch input provided by a user; gestures paths of touchinput; simultaneous touch and stylus input; and so on.

Generally and broadly, the processing unit 222 may be configured toperform, coordinate, and/or manage the functions of the electronicdevice 202. Such functions can include, but are not limited to:communicating with and/or transacting data with other subsystems of theelectronic device 202; communicating with and/or transacting data withthe stylus 204; communicating with and/or transacting data over awireless interface; communicating with and/or transacting data over awired interface; facilitating power exchange over a wireless (e.g.,inductive, resonant, and so on) or wired interface; receiving thelocation(s) and angular position(s) of one or more styluses; and so on.

In many embodiments, the processing unit 222 can include or can becommunicably coupled to circuitry and/or logic components such as aprocessor and a memory. The circuitry of the processing unit 222 cancontrol or coordinate some or all of the operations of the electronicdevice by communicating, either directly or indirectly, withsubstantially all of the subsystems of the electronic device 202. Forexample, a system bus or signal line or other communication mechanismcan facilitate communication between the processing unit 222 and othersubsystems of the electronic device 202.

The processing unit 222 can be implemented as any electronic devicecapable of processing, receiving, or transmitting data or instructions.For example, the processor can be a microprocessor, a central processingunit, an application-specific integrated circuit, a field-programmablegate array, a digital signal processor, an analog circuit, a digitalcircuit, or combination of such devices. The processor may be asingle-thread or multi-thread processor. The processor may be asingle-core or multi-core processor.

During use, the processing unit 222 may be configured to access thememory, which has instructions stored therein. The instructions may beconfigured to cause the processor to perform, coordinate, or monitor oneor more of the operations or functions of the electronic device 202.

The instructions stored in the memory may be configured to control orcoordinate the operation of other components of the electronic device202 such as, but not limited to: another processor, an analog or digitalcircuit, a volatile or non-volatile memory module, a display, a speaker,a microphone, a rotational input device, a button or other physicalinput device, a biometric authentication sensor and/or system, a forceor touch input/output component, a communication module (such as eitherof the wireless interface and/or the power connector), and/or a hapticor tactile feedback device. For simplicity of illustration and to reduceduplication of elements between figures, many of these (and other)components are omitted from FIG. 2C.

The memory can also store electronic data that can be used by the stylusor the processor. For example, the memory can store electrical data orcontent such as media files, documents and applications, device settingsand preferences, timing and control signals or data for various modules,data structures or databases, files or configurations related to thedetection of the tip signal and/or the ring signal, and so on. Thememory can be configured as any type of memory. By way of example, thememory can be implemented as random access memory, read-only memory,flash memory, removable memory, or other types of storage elements, orcombinations of such devices.

The electronic device 202 also includes a power subsystem 224. The powersubsystem 224 can include a battery or other power source. The powersubsystem 224 may be configured to provide power to the electronicdevice 202. The power subsystem 224 can also be coupled to a powerconnector 228. The power connector 228 can be any suitable connector orport that may be configured to receive power from an external powersource and/or configured to provide power to an external load. Forexample, in some embodiments the power connector 228 can be used torecharge a battery within the power subsystem 224. In anotherembodiment, the power connector 228 can be used to transfer power storedwithin (or available to) the power subsystem 224 to the stylus 204.

The electronic device 202 also includes a wireless interface 226 tofacilitate electronic communications between the electronic device 202and the stylus 204. In one embodiment, the electronic device 202 may beconfigured to communicate with the stylus 204 via a low-energy Bluetoothcommunication interface or a Near-Field Communication interface. Inother examples, the communication interfaces facilitate electroniccommunications between the electronic device 202 and an externalcommunication network, device or platform.

The wireless interface 226, whether between the electronic device 202and the stylus 204 or otherwise, can be implemented as one or morewireless interfaces, Bluetooth interfaces, Near Field Communicationinterfaces, magnetic interfaces, universal serial bus interfaces,inductive interfaces, resonant interfaces, capacitive couplinginterfaces, Wi-Fi interfaces, TCP/IP interfaces, network communicationsinterfaces, optical interfaces, acoustic interfaces, or any conventionalcommunication interfaces.

In many embodiments, the wireless interface 226 may be configured tocommunicate directly with the stylus 204 to obtain informationtherefrom. In typical embodiments, the wireless interface 226 can obtaindata related to the force applied by the stylus 204 to the input surface218.

The electronic device 202 also includes a display 230. The display 230can be positioned behind the input surface 218, or can be integratedtherewith. The display 230 can be communicably coupled to the processingunit 222. The processing unit 222 can use the display 230 to presentinformation to a user. In many cases, the processing unit 222 uses thedisplay 230 to present an interface with which the user can interact. Inmany cases, the user manipulates the stylus 204 to interact with theinterface.

It will be apparent to one skilled in the art that some of the specificdetails presented above with respect to the electronic device 202 maynot be required in order to practice a particular described embodiment,or an equivalent thereof. Similarly, other electronic devices mayinclude a greater number of subsystems, modules, components, and thelike. Some submodules may be implemented as software or firmware whenappropriate. Accordingly, it is appreciated that the descriptionpresented above is not meant to be exhaustive or to limit the disclosureto the precise forms recited herein. To the contrary, it will beapparent to one of ordinary skill in the art that many modifications andvariations are possible in view of the above teachings.

Coordination Between the Stylus and the Electronic Device

As noted above, the user input system 200 depicted in FIG. 2A may beconfigured to locate the stylus 204 and to estimate the angular positionof the stylus 204. These operations are facilitated by cooperationbetween the coordination engine 206 of the stylus 204 and thecoordination engine 220 of the electronic device 202. The generalizedinteroperation of these two coordination engines is described above;however, to facilitate a more detailed understanding of the coordinationengine 206 of the stylus 204, FIG. 2D is provided.

FIG. 2D depicts an example system diagram of a coordination engine 206that may be incorporated by a stylus, such as the stylus 204 describedwith reference to FIGS. 2A-2C. As noted with respect to otherembodiments described herein, the coordination engine 206 may be used togenerate electric fields (e.g., the tip field and/or the ring field)which allow the electronic device 202 to locate and estimate the angularposition of the stylus 204.

Additionally, the coordination engine 206 may be configured to estimateforce applied by the stylus 204 to the input surface 218. Morespecifically, the coordination engine 206 may be configured to generatea tip field (not shown), generate and/or emit the ring field (notshown), and to detect the force applied by the tip of the stylus 204 tothe input surface 218. While this is provided as one example, the fieldgeneration and force sensing may, in some embodiments, be performed byseparate aspects of the stylus 204.

In many embodiments, the coordination engine 206 receives the tip signalfrom the processing unit 208 (see, e.g., FIG. 2B) and conveys the tipsignal to a tip-field generator 232. Similarly, the coordination engine206 receives the ring signal from the processing unit 208, and conveysthe ring signal to a ring-field generator 238. In still furtherembodiments, additional electric fields can be generated by additionalfield generators in response to receiving additional field signals.

The tip signal and/or the ring signal can be modulated with otherinformation or data related to the user, the stylus, and/or to theelectronic device. For example, the tip signal and/or the ring signalcan include stylus identity information, user identity information,stylus setting information, force information, or any other informationsuitable for a particular embodiment.

The coordination engine 206 includes a tip-field generator 232. Thetip-field generator 232 can be formed from any number of suitableelectrically conductive materials. The tip-field generator 232 may beconnected to a rigid signal conduit 234. The rigid signal conduit 234can include a rigid portion configured to provide a mechanical couplingbetween components connected to the rigid signal conduit 234.Additionally, the rigid signal conduit 234 can include a core memberthrough which one or more shielded signal lines pass. Example tip-fieldgenerators and rigid signal conduits are described in detail below inreference to FIGS. 3A-6G.

The rigid signal conduit 234 electrically couples the tip-fieldgenerator 232 to a processor, circuit, or electrical trace within thecoordination engine 206. In this manner, the coordination engine 206conveys the tip signal to the tip-field generator 232 via the rigidsignal conduit 234. Additionally, the rigid signal conduit 234mechanically couples the tip-field generator 232 to a force-sensitivestructure 236, described in detail below.

The shape of the rigid signal conduit 234 can be selected so as toprovide electromagnetic shielding to the tip-field generator 232. Moreparticularly, the length of the rigid signal conduit 234 can be selectedso as to separate the tip-field generator 232 by a particular minimumdistance from other electronic components with the stylus 204. As aresult, the tip signal generated by the tip-field generator 232 isaffected as little as possible by the operation of the varioussubsystems of the stylus 204, such as the processing unit 208, the powersubsystem 210, the wireless interface 212, and/or the power connector214, or any other system or subsystem of the stylus 204.

The tip-field generator 232 and the rigid signal conduit 234 can beenclosed entirely within the housing of the stylus 204. In theseembodiments, the tip-field generator 232 can be insert-molded within thehousing material so that the tip-field generator 232 is positioned asclose to the external surface of the stylus 204 as possible. Therelative position of the tip-field generator 232 and housing of thestylus 204 are described below in reference to FIGS. 6A-6G.

In many embodiments, the tip-field generator 232 is formed with arounded shape oriented toward the end of the tip of the stylus 204 thatmay be configured to engage the input surface 218. As a result of thisshape, the tip-field generator 232 may generate an electric field (e.g.,the tip field) that is substantially spherical in nature, at least inthe direction along which the rounded shape of the tip-field generator232 is oriented. In other words, the tip-field generator 232 mayfunction, substantially, as an electric field point source; the electricfield may approach radial uniformity. The tip field generated by thetip-field generator 232 may be axially symmetric.

In some cases, the center of the tip-field generator 232 may be treatedas the origin of the spherical tip field. The input surface 218 may bemathematically modeled as a plane that intersects the spherical tipfield. The tip field intersection area, therefore, takes the shape ofthe intersection of a plane and a sphere, which, regardless oforientation, is a circle. However, although the tip field, the inputsurface, and the tip field intersection area can be mathematicallymodeled as a sphere, a plane, and a circle respectively, it may beappreciated that the actual geometric shapes generated in a particularimplementation may only approximate a sphere, a plane, and/or a circle.

When the tip field is substantially spherical, the tip fieldintersection area is a circular area (or section) within the plane ofthe input surface 218, the center of which may be nearly or preciselyequal to the location of the tip-field generator 232. The radius of thecircular area may be influenced by the amplitude of the tip signalapplied to the tip-field generator 232.

Next, the ring-field generator 238 of the coordination engine 206 isreferenced. As with the tip-field generator 232, the ring-fieldgenerator 238 may be connected, at least partially, to the rigid signalconduit 234. In many examples, the ring-field generator 238 is formedwithin or around the rigid signal conduit 234. For example, thering-field generator 238 can be formed on an external surface of therigid signal conduit 234.

The ring-field generator 238 is coaxially aligned with the tip-fieldgenerator 232 so that the tip field and the ring field are alsocoaxially aligned. In many cases, the ring-field generator 238 isseparated from the tip-field generator 232 by a certain distance. Therelative position of the tip-field generator 232 and the ring-fieldgenerator 238 are described below in reference to FIGS. 5A-5N.

As with the tip-field generator 232, the rigid signal conduit 234electrically couples the ring-field generator 238 to a processor,circuit, or electrical trace within the coordination engine 206. In thismanner, the coordination engine 206 conveys the ring signal to thering-field generator 238 via the rigid signal conduit 234. The rigidsignal conduit 234 also mechanically couples the ring-field generator238 to the force-sensitive structure 236.

The ring-field generator 238 may, in some embodiments, be implemented asan electrically-conductive ring disposed around an external surface ofthe rigid signal conduit 234. The ring-field generator 238 may beseparated from the tip-field generator 232 and may have generallygreater surface area than the tip-field generator 232, although this isnot required of all embodiments. The ring-field generator 238 may beshaped like a ring so as to permit the rigid signal conduit 234 toconvey the tip signal to the tip-field generator 232 in a manner thatdoes not impact the axial symmetry of the ring field. In theseembodiments, the ring field generated by the ring-field generator 238may be axially symmetric.

In these embodiments, the rigid signal conduit 234 includes at least onevia that defines an electrical connection therethrough. In some cases,the via may be formed prior to forming the ring-field generator. Theelectrical connection of the rigid signal conduit 234 electricallycouples a trace disposed within the rigid signal conduit 234 to thering-field generator 238. In many cases, the trace is shielded. As aresult of the shielding, the rigid signal conduit 234 can convey ashielded ring signal to the ring-field generator 238.

The ring-field generator 238 can be formed from any number of suitableelectrically conductive materials. In some examples, the ring-fieldgenerator 238 is formed from metal. In other cases, the ring-fieldgenerator 238 is formed from a deposited electrically conductivematerial, such as a metal-oxide or a metal powder. Example ring-fieldgenerators are described in detail below with reference to FIGS. 5A-5N.

Because the ring-field generator 238 is separated from the tip of thestylus 204, the angular position of the stylus 204 (rotated from thetip) affects the distance between the input surface 218 and thering-field generator 238. For example, if the stylus 204 touches theinput surface 218 at a very acute angle (e.g., the stylus lyingsubstantially flat on the input surface), the ring-field generator 238may be a small distance from the input surface. Conversely, if thestylus 204 is normal to the input surface 218 (e.g., ninety degreeangle), the ring-field generator 238 is positioned a large distance fromthe input surface 218. In this manner, the ring-field generator 238traverses an arc above the input surface 218 when the polar angle of thestylus 204 changes; the apex of the arc occurs when the stylus 204 isnormal to the input surface 218.

As may be appreciated, the foregoing generalized description referencesthe coordination engine 206 of the stylus 204 as it relates to thegeneration of a tip field and a ring field that can be detected by thecoordination engine 220 of electronic device 202. As noted above, thecoordination engine 220 of the electronic device 202 can be configuredto detect the tip field and the ring field and, correspondingly, the tipfield intersection area and the ring field intersection area. Theelectronic device 202 thereafter compares the relative positions of thetip field intersection area and the ring field intersection area inorder to estimate the location of the stylus and the angular position ofthe stylus. In this manner, the coordination engine 206 and thecoordination engine 220 cooperate to determine, with high accuracy, thelocation and angular position of the stylus 204 relative to the plane ofthe input surface 218 of the electronic device 202.

In many examples, the cooperation of the coordination engines 206, 220permit the user input system 200 to operate in a more power-efficientmanner than conventional stylus input systems that include a separateelectromagnetic digitizer that serves a dual purpose of powering thestylus (e.g., inductive power, resonant inductive coupling, and so on)and receiving and interpreting input therefrom. Further, the processingpower required of the coordination engine 220 may be less than theprocessing power required by the conventional stylus input system thatincludes an electromagnetic digitizer. Thus, the user input systemembodiments described herein can operate with reduced latency overconventional stylus input systems.

The coordination engine 206 can also estimate a magnitude of forceapplied by the tip of the stylus 204 to the input surface 218. Oneexample method of detecting a magnitude of force applied by the stylus204 to the input surface 218 is described below; however, it may beappreciated that this is merely one example and that other embodimentscan detect the force applied by the stylus 204 in anotherimplementation-specific and suitable manner.

As noted above with respect to other embodiments, the tip of the stylus204 can be movable with respect to the body of the stylus 204, generallyalong the longitudinal axis (e.g., the longitudinal axis 120 as shown inFIG. 1A). More particularly, the tip-field generator 232, the ring-fieldgenerator 238, and/or the rigid signal conduit 234 may be configured toat least partially shift, translate, withdraw, or otherwise changeposition along an axial direction with respect to the housing of thestylus 204 in response to a force applied by the tip of the stylus 204to the input surface 218.

The rigid signal conduit 234 can couple the tip of the stylus 204 to theforce-sensitive structure 236 of the coordination engine 206. In thismanner, when the tip of the stylus 204 touches the input surface 218 (orany other surface), and applies a force, the tip of the stylus 204experiences a reaction force which, in turn, is transferred via therigid signal conduit 234 to the force-sensitive structure 236.

In these embodiments, the force-sensitive structure 236 also includes asensor that exhibits an electrically-measurable property that changes asa function of the magnitude of force applied to the force-sensitivestructure. In one example, the sensor is sensitive to strain and may becoupled to the rear cantilevered leg of the force-sensitive structure236. In this manner the strain sensor is physically separated from bothof the tip-field generator 232 and the ring-field generator 238 by adistance that reduces any parasitic coupling, electromagneticinterference, or any other interference between the strain sensor andthe tip-field generator 232 and the ring-field generator 238.

In one embodiment, the strain sensor operates as a resistive sensorformed from a material that exhibits a change in electrical resistance(e.g., conductance) in response to a dimensional change such ascompression, tension, or force. The strain sensor can be a compliantmaterial that exhibits at least one electrical property that is variablein response to deformation, deflection, or shearing of the electrode.The strain sensor may be formed from a piezoelectric, piezoresistive,resistive, or other strain-sensitive materials.

The force-sensitive structure 236 is configured to deflect relative tothe frame of the body of the stylus in response to a force applied bythe tip of the stylus. As a result of the deflection, theelectrically-measurable property of the sensor can change. Thus, bymeasuring the electrical property of the sensor, a force estimate can beobtained by the coordination engine 206. The force estimate may be anestimation of the magnitude of the reaction force acting on the stylus204. Once a force estimate is obtained, the coordination engine 206communicates the force estimate to the electronic device 202 as a vectoror scalar quantity using any suitable encoded or not-encoded format.

Main Controller Subsystem of the Stylus

As noted above, the user input system 200 depicted in FIG. 2A may beconfigured to locate the stylus 204 and to estimate the angular positionof the stylus 204 based on the cooperation between the coordinationengines 206, 220. In many embodiments, other information can beexchanged between the electronic device 202 and the stylus 204, such as,but not limited to: applied force magnitude; battery capacity of thestylus 204; stylus setting information; user identity information;stylus identity information; and so on.

As noted above, such information can be conveyed from the stylus 204 tothe electronic device 202 by modulating said information as a digital oranalog data signal over either or both the tip signal and the ringsignal. In other cases, however, a separate communication technique canbe used. In many examples, these additional operations and functions ofthe stylus are performed, monitored, and/or coordinated by a processingunit and a wireless interface, such as the processing unit 208 and thewireless interface 212 as of the stylus 204 as shown in FIG. 2B.

Next reference is made to FIG. 2E, in which a simplified system diagramof the processing unit 208 and the wireless interface 212 of the stylus204 of FIG. 2B is shown. The processing unit 208 may be configured tofacilitate communication between the coordination engine 206, the powersubsystem 210, the wireless interface 212, and/or the power connector214 (as shown in FIGS. 2A-2B). These operations and purposes of theprocessing unit 208 are merely examples; different embodiments may taskthe processing unit 208 differently.

The processing unit 208 can include a processor 240, a memory 242, asensor 244, and a signal generator 246. The processor 240 can control orcoordinate some or all of the operations of the processing unit 208 bycommunicating, either directly or indirectly, with substantially all ofthe components of the processing unit 208 and/or other subsystems of thestylus 204. For example, a system bus or signal line or othercommunication mechanism can facilitate communication between theprocessor 240 and various components of the processing unit 208 or, moregenerally, other subsystems of the stylus 204.

The processor 240 can be implemented as any electronic device capable ofprocessing, receiving, or transmitting data or instructions. Theprocessor 240 may be configured to access the memory 242, which hasinstructions stored therein. The instructions may be configured to causethe processor 240 to perform, coordinate, or monitor one or more of theoperations or functions of the processing unit 208 and/or the stylus204.

In many embodiments, one or more components of the processor 240 caninclude or can be communicably coupled to circuitry and/or logiccomponents, such analog circuitry, digital circuitry, and the memory242. The circuitry can facilitate some or all of the operations of theprocessor 240 including, but not limited to: communicating with and/ortransacting data with other subsystems of the stylus 204; generatingparameters used to generate the tip signal and the ring signal;conveying the tip signal and the ring signal to the coordination engine206; measuring and/or obtaining the output of one or more analog ordigital sensors, such as a strain sensor or accelerometer; and so on.

In some cases, the processor 240 and the memory 242 are implemented inthe same integrated circuit (which may be a surface-mounted integratedcircuit), although this is not required of all embodiments.

The instructions stored in the memory 242 may be configured to controlor coordinate the operation of a separate processor, an analog ordigital circuit, a volatile or non-volatile memory module, a display, aspeaker, a microphone, a rotational input device, a button or otherphysical input device, a biometric authentication sensor and/or system,a force or touch input/output component, a communication module (such asthe wireless interface 212), and/or a haptic or tactile feedback device.For simplicity of illustration and to reduce duplication of elementsbetween figures, many of these (and other) components are omitted fromone or more of the simplified system diagrams depicted in FIGS. 2A-2Band 2E. It may be understood that many of these elements and componentsmay be included either entirely or partially within the housing of thestylus 204 and may be integrated in an appropriate andimplementation-specific manner into many embodiments described herein.

The memory 242 can also store electronic data that can be used by thestylus 204 or the processor 240. For example, the memory 242 can storeelectrical data or content such as, but not limited to: media files;documents and applications; device settings and preferences; timing andcontrol signals or data for various modules or subsystems of the stylus204; data structures or databases, files, parameters, or configurationsrelated to the tip signal and/or the ring signal; and so on.

The memory 242 can be configured as any type of memory. By way ofexample, the memory 242 can be implemented as random access memory,read-only memory, flash memory, removable memory, or other types ofstorage elements, or combinations of such devices.

The processor 240 may be configured to obtain data from one or moresensors, collectively labeled as the sensor 244. The sensor 244 can bepositioned substantially anywhere on the processing unit 208 or, moregenerally, anywhere within the housing of the stylus 204. For example,one sensor of the sensor 244 may be the sensor coupled to theforce-sensitive structure 236 (see, e.g., FIG. 2D).

In some embodiments, the sensor 244 is configured to detectenvironmental conditions and/or other aspects of the operatingenvironment of the stylus 204. For example, an environmental sensor maybe an ambient light sensor, proximity sensor, temperature sensor,barometric pressure sensor, moisture sensor, and the like. In othercases, the sensors may be used to compute an ambient temperature, airpressure, and/or water ingress into the stylus 204. Such data may beused by the processor 240 to adjust or update the operation of thestylus 204 and/or may communicate such data to the electronic device 202to adjust or update the operation thereof.

In still further embodiments, the sensor 244 is configured to detectmotion characteristics of the stylus 204. For example, a motion sensormay include an accelerometer, a gyroscope, a global positioning sensor,a tilt sensor, and so on for detecting movement and acceleration of thestylus 204. Such data may be used to adjust or update the operation ofthe stylus 204 and/or may communicate such data to the electronic device202 to adjust or update the operation thereof.

In still further embodiments, the sensor 244 is configured to biologicalcharacteristics of the user manipulating the stylus 204. An examplebiosensor can detect various health metrics, including skin temperature,heart rate, respiration rate, blood oxygenation level, blood volumeestimates, blood pressure, or a combination thereof. The processor 240can use such data to adjust or update the operation of the stylus 204and/or may communicate such data to the electronic device 202 to adjustor update the operation thereof.

The stylus 204 may also include one or more utility sensors that may beused to estimate, quantify, or estimate a property of an object nearbyor otherwise external to the stylus 204. Example utility sensors includemagnetic field sensors, electric field sensors, color meters, acousticimpedance sensors, pH level sensor, material detection sensor, and soon. The processor 240 can use such data to adjust or update theoperation of the stylus 204 and/or may communicate such data to theelectronic device 202 to adjust or update the operation thereof.

In many cases, the processor 240 can sample (or receive samples of)external data, motion data, power data, environmental data, utilitydata, and/or other data, and track the progress thereof over a definedor undefined period of time. The cumulative tracked data, the rate ofchange of the tracked data, the average of the tracked data, the maximumof the tracked data, the minimum of the tracked data, the standarddeviation of the tracked data, and so on, can all be used to adjust orupdate the operation of the stylus 204 and/or may communicate such datato the electronic device 202 to adjust or update the operation thereof.

The wireless interface 212 can be communicably coupled to the processor240 and may include one or more wireless interface(s) that are adaptedto facilitate communication between the processor 240 and a separateelectronic device, such as the electronic device 202. In general, thewireless interface 212 may be configured to transmit and receive dataand/or signals that may be interpreted by instructions executed by theprocessor 240.

The wireless interface 212 can include radio frequency interfaces,microwave frequency interfaces, cellular interfaces, fiber opticinterfaces, acoustic interfaces, Bluetooth interfaces, infraredinterfaces, magnetic interfaces, electric field interfaces, UniversalSerial Bus interfaces, Wi-Fi interfaces, Near-Field Communicationinterfaces, TCP/IP interfaces, network communications interfaces, or anyother wireless communication interfaces. In many embodiments, thewireless interface 212 may be a low-power communication module, such asa low-power Bluetooth interface. The wireless interface 212 may be atwo-way communication interface or a one-way communication interface.

In one embodiment, the processor 240 utilizes the wireless interface 212to convey information about the stylus 204 to the electronic device 202,substantially in real-time. For example, such information can be, but isnot limited to: real-time, or substantially real-time, force estimationsmade by the coordination engine 206 and/or the processor 240 as a resultof measuring the sensor of the force-sensitive structure 236; real-time,or substantially real-time, angular position estimations made by theprocessor 240 after obtaining data from an accelerometer or gyroscopewithin the stylus 204; and so on.

The processor 240 can also be in communication with a signal generator246. The signal generator 246 may be configured to generate the tipsignal and the ring signal, conveyed by the coordination engine 206 tothe tip-field generator 232 and the ring-field generator 238respectively (see, e.g., FIGS. 2B and 2D). In other examples, the signalgenerator 246 generates, stores, accesses, or modifies tip and/or ringsignal parameters that are conveyed to the coordination engine 206. Thecoordination engine 206 can receive these parameters and, in response,can generate a corresponding tip signal and ring signal.

In some examples, the signal generator 246 can include stylus or useridentifying information within either or both of the tip signal and/orthe ring signal. For example, the signal generator 246 can includeinformation that identifies a particular stylus to a particularelectronic device. In these embodiments, more than one stylus (eachhaving a different identity) can be used with the same electronic device202. In some cases, multiple styluses can be associated with differentfunctions and/or operations of the electronic device 202. In oneexample, a series of individually-identifiable styluses can be used toperform separate tasks within a graphical illustration program operatingon the electronic device.

In other examples, the signal generator 246 can include authenticationinformation within either or both of the tip signal and/or the ringsignal. In these cases, a particular user of a particular stylus can beidentified to an electronic device. For example, a stylus may includeone or more bioauthentication sensors, such as fingerprint sensors,useful to establish the identity of a user manipulating the stylus. Inthis embodiment, the signal generator 246 can encode authenticationinformation (e.g., public keys, security certificates, and so on) intoeither or both the tip signal or the ring signal. Thereafter, theelectronic device can decode and/or demodulate the received tip signaland/or ring signal in order to obtain the authentication informationprovided. The electronic device may, thereafter, estimate whether theobtained authentication information is associated with a user identityknown or knowable to the electronic device. A known user may be grantedauthority to operate certain features of the electronic device or toaccess certain information available to or accessible by the electronicdevice.

Power Subsystem of the Stylus

As noted above, the user input system 200 depicted in FIG. 2A may beconfigured to locate the stylus 204, estimate the angular position ofthe stylus 204, and to facilitate direct communication between theelectronic device 202 and the stylus 204. Next, reference is made to thepower subsystem 210 of the stylus 204, as depicted in FIG. 2F.

Generally and broadly, the power subsystem 210 of the stylus 204 may beconfigured to store and provide power to various components and othersubsystems of the stylus 204. The power subsystem 210 generally includesa charge/discharge controller 248, a charge monitor 250, and a battery252.

The charge monitor 250 may be configured to estimate the capacity of thebattery 252 at a particular time. The charge/discharge controller 248may be implemented as a processor and power regulator that may beconfigured to control the voltage and/or current supplied to the battery252 when in a charging mode and, separately, to control the voltageand/or current supplied by the battery 252 when in a discharging mode.

The charge/discharge controller 248 is also coupled to the powerconnector 214. When the power connector 214 is coupled to a power source(e.g., a powered data port, such as the data port 114 of the electronicdevice 102 shown in FIG. 1A), the charge/discharge controller 248 canconvey power received therefrom to the battery 252 in order to replenishthe charge of the battery 252.

In one embodiment, the charge/discharge controller 248 may be configuredto permit rapid charging of the battery 252 without causing damage tothe battery 252. In some cases, the charge/discharge controller 248 maybe configured to slow the charging rate once the battery 252 has beenrecharged beyond a selected threshold capacity. For example, thecharge/discharge controller 248 may be configured to operate in a fastcharging mode (e.g., high constant current) until the capacity of thebattery 252 is estimated to be greater than eighty percent. Thereafterthe charge/discharge controller 248 may slow the charging rate to a rateselected so as to prevent permanent damage to the battery 252.

The battery 252 may be a lithium-polymer battery or a lithium ionbattery. However, in other embodiments, alkaline batteries,nickel-cadmium batteries, nickel-metal hydride batteries, or any othersuitable rechargeable or one-time-use batteries may be used.

For embodiments in which the battery 252 is a lithium-polymer battery,the battery 252 may include stacked layers that may form the componentsof the battery 252 (e.g., anode, cathode). In many embodiments, thebattery 252 may be rolled prior to being sealed in a pouch. In thismanner, the battery 252 may have little or no unused space whenpositioned within the body of the stylus 204.

The battery 252 includes a cathode, an electrolyte, a separator, and ananode. The cathode (or positive electrode) may be a layered oxide, suchas lithium cobalt oxide (LiCoO₂), a polyanion, such as lithium ironphosphate, or a spinel, such as lithium manganese oxide. The cathode mayinclude a solution having an active material (e.g., LiCoO₂), aconductive additive (e.g., carbon black, acetylene black, carbon fibers,graphite, etc.), a binder (such as polyvinyledene fluoride,ethylene-propylene, and a diene), and optionally a solvent. The bindercan act to hold the active material and the conductive additivetogether, and in instances where the binder is non-water soluble thesolvent (such as N-methypyrrolidone), acts to distribute the activematerial and conductive additive throughout the binder. It should benoted that the above examples of the cathode solution are meant asillustrative only and many other conventional cathode materials may beused to form the cathode.

The anode (or negative electrode) is generally the source of ions andelectrons for the battery 252. The anode may include an anode solutionincluding an active material (e.g., lithium, graphite, hard carbon,silicon, or tin), a conductive additive (e.g., carbon black, acetyleneblack, or carbon fibers), a binder (such as polyvinyledene fluoride,ethylene-propylene, and a diene), and optionally a solvent.

The separator may be positioned between the cathode and the anode. Theseparator may be a fiberglass cloth or flexible plastic film (e.g.,nylon, polyethylene, or polypropylene). The separator separates theanode and cathode while allowing the charged lithium ions to passbetween the anode and cathode.

The electrolyte may be a mixture of organic carbonates such as ethylenecarbonate or diethyl carbonate containing complexes of lithium ions.These non-aqueous electrolytes generally use non-coordinating anionsalts such as lithium hexafluorophosphate (LiPF₆), lithiumhexafluoroarsenate monohydrate (LiAsF₆), lithium perchlorate (LiClO₄),lithium tetrafluoroborate (LiBF₄), and lithium triflate (LiCF₃SO₃). Theelectrolyte may be filled into the anode and/or cathode around the anodeand cathode solutions. In some embodiments, the electrolyte may besaturated into the separator, such that as the separator is added to thecore, the electrolyte may be added as well.

In some embodiments, the battery 252 may include one or more othercomponents, such as flow barriers and/or encapsulation walls operablyconnected to either or both the cathode electrode collector and theanode electrode collector, among other components. The particularconfiguration of the battery 252 described above is merely a simplifiedexample, and the number and order of the individual components may vary.

As with the specific embodiments depicted in FIGS. 1A-1D, the foregoingdescription of the embodiments depicted in FIGS. 2A-2F, and variousalternatives and variations, are presented, generally, for purposes ofexplanation, and to facilitate a thorough understanding of generaloperation and function of an input system such as described herein.

However, it will be apparent to one skilled in the art that some of thespecific details presented herein may not be required in order topractice a particular described embodiment, or an equivalent thereof.Thus, the foregoing and following descriptions of specific embodimentsare presented for the limited purposes of illustration and description.These descriptions are not targeted to be exhaustive or to limit thedisclosure to the precise forms recited herein. To the contrary, it willbe apparent to one of ordinary skill in the art that many modificationsand variations are possible in view of the above teachings.Particularly, it may be understood that the operational characteristicsof the user input system depicted in FIGS. 2A-2F, including theoperation of the electronic device and the operation of the stylus, canbe implemented in a number of suitable and implementation-specific ways.

Component Layout of the Stylus

As noted with respect to many embodiments described herein, a stylusconfigured to generate a tip field and a ring field (which may bedetected by a coordination engine of an electronic device) may beconstructed in a manner that serves to reduce or eliminate parasiticcoupling, electromagnetic interference, or any other interference thatmay negatively affect the tip field and/or ring field. Generally andbroadly, embodiments described herein physically separate electroniccomponents and circuits within a stylus from the tip-field generator andring-field generator. Additionally, certain structural components withinthe stylus are configured to serve as electromagnetic shields benefitingthe tip-field generator, the ring-field generator, and/or signal linesassociated therewith. One such example stylus is described below withreference to FIG. 3A; however, it may be appreciated that the shieldingtechniques and generalized layout presented therein and described beloware merely one example and that other embodiments can be implemented indifferent ways.

FIG. 3A depicts various components of a stylus 300 in an exploded view.To facilitate an understanding of the interoperation and assembly of thevarious components of the stylus 300, FIGS. 3D-3G are provided, showingthe fully-assembled stylus 300 (e.g., FIG. 3D), a detailed view of anassembled tip end of the stylus 300 (e.g., FIG. 3E), a detailed view ofan assembled middle portion of the stylus 300 (e.g., FIG. 3F), and adetailed view of an assembled blind cap end of the stylus 300 (e.g.,FIG. 3G). For simplicity of illustration, some portions of theembodiments depicted in FIGS. 3D-3G are provided in phantom or areillustrated to be semi-transparent.

The stylus 300 of the illustrated embodiment includes a barrel 302. Thebarrel 302 is hollow. The barrel 302 may take various forms tofacilitate convenient, familiar, and comfortable manipulation or thestylus 300 by a user. In the illustrated example, the barrel 302 has thegeneral form of a writing instrument, such as a pen or a pencil. Thebarrel 302 is generally cylindrical with a constant diameter. The barrel302 can be formed from plastics, metals, ceramics, laminates, glass,sapphire, wood, leather, synthetic materials, or any other material orcombination of materials.

The barrel 302 can be configured to connect to a blind cap 304 at an endof the barrel 302. The blind cap 304 may be configured to provide acosmetic end to the barrel 302 of the stylus 300. The blind cap 304forms a substantially continuous external surface with the barrel 302when attached to the barrel 302.

In some cases, the blind cap 304 includes a clip (not shown) forattaching the stylus 300 to a user's pocket, or any other suitablestorage location. The blind cap 304 can include a through-holeconfigured to couple to a lanyard or tether. The lanyard or tether mayalso be configured to couple to an electronic device.

The blind cap 304 may be formed from any suitable material, such as, butnot limited to, metal, plastic, glass, ceramic, sapphire, and the likeor combinations thereof. In many cases, the blind cap 304 is formed fromthe same material as the barrel 302, although this is not required. Insome embodiments, the blind cap 304 may be configured, entirely orpartially, as a signal diffuser to diffuse an infrared signal or anotheroptical signal, such as a multi-color light-emitting diode. In othercases, the blind cap 304 may be configured, entirely or partially, as anantenna window, allowing for wireless communications and/or electricfields to pass therethrough.

As illustrated, the blind cap 304 terminates in a rounded end, althoughthis is not required of all embodiments. In some embodiments, the blindcap 304 terminates as a plane. In other embodiments, the blind cap 304terminates in an arbitrary shape.

The blind cap 304 can exhibit a constant or a variable diametercross-section. In many embodiments, such as illustrated, thecross-section view of the blind cap 304 matches that of the barrel 302where the barrel 302 and the blind cap 304 interface.

The blind cap 304 can be configured to be removably attached to thebarrel 302. In one embodiment, the blind cap 304 is threaded such thatthe blind cap 304 screws into corresponding threads within the barrel302. In other cases, the blind cap 304 includes one or more detentsand/or recesses that are configured to align with one or morecorresponding recesses and/or detents within the barrel 302 and/or theconnector that the blind cap 304 may conceal. In other cases, the blindcap 304 is interference-fit to the barrel 302. In still further cases,the blind cap 304 is magnetically attracted to a portion of the barrel302.

In the illustrated embodiment, the barrel 302 tapers at one end. Thetapered end of the barrel 302 is identified in the figure as the taperedtip 302 a. The tapered tip 302 a of the barrel 302, which is oppositethe end of the barrel 302, may be configured to connect to the blind cap304 to partially enclose and support a point assembly 306 (see, e.g.,FIGS. 3D-3E).

As illustrated, the tapered tip 302 a may be formed integrally with thebarrel 302. In other embodiments, the tapered tip 302 a is a separatepiece from the barrel 302. For example, the tapered tip 302 a can beadhered to the barrel 302, sonic-welded to the barrel 302, snap-fit tothe barrel 302, friction fit to the barrel 302, or connected to thebarrel 302 in any other suitable manner.

The point assembly 306 is partially disposed within the tapered tip 302a. Other portions of the point assembly 306 are attached, eitherpermanently or removably, to the end of the tapered tip 302 a from theexterior thereof. The point assembly 306 is itself configured toenclose, retain, and/or support various electronic components associatedwith a tip-field generator, a ring-field generator, and astrain-responsive element of the stylus 300, all of which are referencedand described in detail below.

The point assembly 306 can include a grounded portion 306 a and amovable portion 306 b. The movable portion 306 b of the point assembly306 may be movable with respect to the barrel 302. The grounded portion306 a of the point assembly 306 may be fixed with respect to the barrel302, or a chassis thereof.

The movable portion 306 b of the point assembly 306 includes a nosepiece308. The nosepiece 308 generally takes a conical shape, however such ashape is not required of all embodiments. The nosepiece 308 includes acollar 308 a and a nib 308 b.

In many cases, the nosepiece 308 can be replaceable and/or removable bya user. For example, different nosepieces can take different shapes. Auser may prefer, in some examples, to swap the nosepiece 308 for anosepiece having a specific shape. Example nosepiece shapes include, butare not limited to: point shapes of different size; chisel shapes; flatshapes; fountain pen tip shapes; and so on.

The nosepiece 308 can be formed of a single material. In other cases,the collar 308 a is formed from a first material and the nib 308 b isformed from a second material. The nosepiece 308 can be manufactured bya two-shot molding process, a co-molding process, an overmoldingprocess, an insert molding process, or any other suitable process.

The collar 308 a may be configured to removably or permanently engagewith a portion of a coordination engine 310 (described in detail below)disposed within the barrel 302. The coordination engine 310 includes arigid signal conduit 310 a and a force-sensitive structure 310 b. Therigid signal conduit 310 a is configured to electrically andmechanically couple the movable portion 306 b of the point assembly 306to the force-sensitive structure 310 b (see, e.g., FIGS. 3D-3E).

More specifically, the collar 308 a can include a threaded portion thatmay be configured to engage with corresponding threads of the rigidsignal conduit 310 a. In this embodiment, the collar 308 a may tightlyabut a boss attached to the rigid signal conduit 310 a so that torquesexperienced by the nosepiece 308 during manipulation of the stylus 300by the user does not cause the collar 308 a to rotate and/or disengagefrom the rigid signal conduit 310 a.

In other embodiments, the collar 308 a may be configured to engage therigid signal conduit 310 a in a different manner, such as with asnap-fit or a friction fit. In still further examples, the collar 308 acan be permanently attached to the rigid signal conduit 310 a, forexample using an adhesive or by welding.

Once the collar 308 a is attached to the rigid signal conduit 310 a, thenosepiece 308 may be movable with respect to the barrel 302. Morespecifically, the nosepiece 308 may be permitted to withdraw by acertain distance into the barrel 302 in response to a reaction forcesuch as described above.

In some implementations, when assembled into the barrel 302, thenosepiece 308 is separated from the tapered tip 302 a by a clearance gap312, such as shown in FIG. 3B. Herein, this state of the stylus 300 isgenerally referred to as a “ready” state.

In the ready state, the clearance gap 312 can have any suitable width;however, for typical embodiments, the clearance gap 312 may be less than1 millimeter when in a neutral position (e.g., when the stylus 300 isnot applying a force to any surface and no reaction force is acting toclose the clearance gap 312). In other embodiments, the clearance gap312 may be less than 0.1 millimeters when in a neutral position. Inother embodiments, the clearance gap 312 has a different width. In someexamples, the width of the clearance gap 312 is configurable by rotatingthe nosepiece 308. In one embodiment, the user rotates the nosepiece308, causing the collar 308 a to advance along the threads of the rigidsignal conduit 310 a, toward the barrel 302, thereby reducing theclearance gap 312. In another embodiment, the user is able to rotate thenosepiece 308, causing the collar 308 a to retreat from the threads ofthe rigid signal conduit 310 a, away from the barrel 302, therebyincreasing the clearance gap 312.

In some examples, the width of the clearance gap 312 in the ready statecan be selected, at least in part, to reduce the peak mechanical loadexperienced by the coordination engine or, more generally, electrical ormechanical components disposed within the barrel 302. More specifically,the clearance gap 312 may be configured to be fully closed after thenosepiece 308 receives a reaction force F_(r) beyond a certain threshold(e.g., 1 kilogram in one embodiment, 0.5 kilograms in anotherembodiment), such as shown in FIG. 3C. Once the clearance gap 312 isfully closed, the nib 308 b directly contacts the tapered tip 302 a,thereby preventing components within the barrel 302, such as thecoordination engine, from experiencing a reaction force greater than athreshold magnitude. As described below with respect to FIG. 7, one ormore adjustable internal components may be used to limit the travel ofthe nosepiece 308 and/or the force transmitted to internal components,such as, but not limited to, a force-sensitive structure.

In some embodiments, the clearance gap 312 can be filled with acompliant material, such as an elastomer or a polymer. In otherexamples, a deformable or compressible material can cosmetically bridgethe clearance gap 312, connecting the nosepiece 308 to the tapered tip302 a of the barrel 302.

Returning to FIG. 3A, the nib 308 b of the nosepiece 308 of the pointassembly 306 may be configured to contact an input surface of anelectronic device. The nib 308 b may taper to a point, similar to a pen,so that the user may control the stylus 300 with precision in a familiarform factor. In some examples, the nib 308 b may be blunt or rounded, asopposed to pointed, or may take the form of a rotatable or fixed ball.

In many embodiments, the nib 308 b is formed from a softer material thanthe input surface of the electronic device (such as the electronicdevice 102 depicted in FIG. 1A). For example, the nib 308 b can beformed from (or may have an external surface or coating formed from) asilicone, a rubber, a fluoroelastomer, a plastic, a nylon, or any othersuitable material or combination of materials. In this manner, drawingof the nib 308 b across the input surface may not cause damage to theinput surface or layers applied to the input surface such as, but notlimited to, anti-reflective coatings, oleophobic coatings, hydrophobiccoatings, cosmetic coatings, ink layers, and the like.

The nib 308 b can be formed from a material doped with an agentconfigured to provide the nib 308 b with a selected color, hardness,elasticity, stiffness, reflectivity, refractive pattern, texture and soon. In other examples, the doping agent can confer other properties tothe nib 308 b including, but not necessarily limited to, electricalconductivity and/or insulating properties, magnetic and/or diamagneticproperties, chemical resistance and/or reactivity properties, infraredand/or ultraviolet light absorption and/or reflectivity properties,visible light absorption and/or reflectivity properties, antimicrobialand/or antiviral properties, oleophobic and/or hydrophobic properties,thermal absorption properties, pest repellant properties, colorfastand/or anti-fade properties, antistatic properties, liquid exposurereactivity properties, and so on. In many cases, the nib 308 b is formedfrom the same material as the barrel 302, although this is not required.

A tip-field generator 314 is disposed within a tip end of the nib 308 b(see, e.g., FIGS. 3D-3E). In many embodiments, the tip-field generator314 is insert molded into the nib 308 b, although this may not berequired of all embodiments. The tip-field generator 314 may be disposedas near to the external surface of the nib 308 b as possible.

As noted above, the point assembly 306 also includes several componentsthat may be disposed within and fixed with respect to the barrel 302. Intypical embodiments, the point assembly 306 includes a support collar316 and a flanged nut 318. In some embodiments, such components can beformed as integral components.

In many embodiments, the flanged nut 318 can be welded, soldered, orotherwise permanently adhered to a chassis 320. The chassis 320 can takethe shape of a sleeve that inserts within the barrel 302. The chassis320 can be fixed with respect to an interior surface of the barrel 302(see, e.g., FIGS. 3D-3G; the chassis 320 is depicted assemi-transparent). The support collar 316 can be connected to theflanged nut 318. In some examples, the support collar 316 abuts a lip orring within an interior surface of the barrel 302 (not visible).

The chassis 320 is configured to slide into the interior volume of thebarrel 302 and may provide structural support mounting features for thevarious internal components of the stylus 300. The chassis 320 has ashape that corresponds to the shape of the barrel 302. In this case, thechassis 320 takes a substantially cylindrical shape, which correspondsto a cylindrical shape of the internal volume of the barrel 302. Thechassis 320 may be sized so as to extend across the majority of thelength of the barrel 302, although this may not be required in allembodiments (see, e.g., FIG. 3D).

In some examples, the chassis 320 can include one or more electricallyinsulating layers disposed on an exterior surface thereof. Theelectrically insulating layers can prevent the chassis 320 frominterfering with the operation of one or more circuits within the stylus300. The electrically insulating layers may be formed from an ink,coating, or separate component adhered or otherwise fixed to the innersurface of the chassis 320.

In some examples, the chassis 320 can include one or more electricallyinsulating layers disposed on an exterior surface thereof. Theelectrically insulating layers can prevent the chassis 320 frominterfering with the operation of one or more circuits within the stylus300.

In other examples, the chassis 320 can be electrically connected to oneor more circuits. In many examples, the chassis 320 can serve as asystem ground, proving an electrical ground for all (or substantiallyall) the electrical circuits disposed within the stylus 300. In othercases, the chassis 320 can also serve as a ground plane for one or moreantenna elements.

In some embodiments, one or more wireless components are positionedwithin the chassis 320 and are configured to transmit signals to one ormore external devices. To facilitate the transmission of these signals,the chassis 320 may include an antenna window 322. The antenna window322 is an aperture sized to permit electromagnetic signals generated byan antenna assembly 324 to exit the barrel 302. The size and location ofthe antenna window 322 depends, at least in part, on the size andlocation of the antenna assembly 324.

Although in the illustrated embodiment the chassis 320 defines anantenna window 322, other embodiments can include more than one antennawindow (see, e.g., FIG. 3D and FIG. 3G). In some examples, more than oneantenna assembly can share the same antenna window, or, in other cases,each antenna assembly can be positioned within or adjacent to its owndedicated antenna window.

The chassis 320 may also include an access or assembly window 326. Theassembly window 326 may be included to facilitate simplifiedmanufacturing of the stylus 300. For example, the assembly window 326can be defined in the chassis 320 adjacent a location at which a hot baroperation is desired or preferred to electrically couple one componentto another, when both components are already disposed within the chassis320. In other examples, the assembly window 326 can be defined in theassembly window 326 adjacent to a location at which a connection betweentwo separate circuits is made via a connector.

As may be appreciated, certain embodiments can define the chassis 320with more than one assembly window. In other cases, an assembly windowmay not be required.

In some examples, the assembly window 326 may be covered once themanufacturing operation necessitating the assembly window 326 iscompleted. In some cases, the assembly window 326 can be covered by anelectrically conductive tape. In another case, the assembly window 326can be covered by welding a plate over the assembly window 326. As maybe appreciated, the cover disposed over the assembly window 326 incertain embodiments may be electrically conductive in order to provideelectromagnetic shielding to the electronic elements that are disposedwithin the chassis 320.

The chassis 320 can also include a bonding point 328. In the illustratedembodiment, the chassis 320 has two bonding points, labeled as a bondingpoint 328 and a bonding point 330. The bonding points 328, 330 can beformed with geometry that facilitates bonding to another component. Forexample, a bonding point can be prepared for welding to another metalmaterial. Preparing a bonding point for welding may include any numberof operations including, but not limited to: removing one or morecoatings applied to the material selected for the chassis 320; scoringthe bonding point; adding sacrificial material to the bonding point;forming the bonding point into a particular geometry; and so on.

Although the bonding points of the chassis 320 are depicted as beingdefined in the same half of the chassis 320, it is appreciated thatbonding points can be appropriately defined at a location along thechassis 320. In many embodiments, the bonding points 328, 330 of thechassis 320 are configured to be welded to a force-sensitive structure310 b (see, e.g., FIGS. 3D-3E).

The force-sensitive structure 310 b can be formed, at least in part,from metal. The force-sensitive structure 310 b can include a lateralbed 332 with two cantilevered legs extending from each end of thelateral bed 332. The cantilevered legs are identified in the illustratedembodiment as the rear cantilevered leg 334 and the front cantileveredleg 336.

The rear cantilevered leg 334 and the front cantilevered leg 336 can beformed from the same material as the lateral bed 332. In someembodiments, the lateral bed 332 and the rear cantilevered leg 334 andthe front cantilevered leg 336 are formed as a single, integral part. Inother examples, the rear cantilevered leg 334 and the front cantileveredleg 336 are attached to the lateral bed 332 via adhesive, welding, orany other suitable method.

In some cases, the rear cantilevered leg 334 and the front cantileveredleg 336 can be coupled to the lateral bed 332 by a pivoting or hingingconnection.

Both of the rear cantilevered leg 334 and the front cantilevered leg 336can provide a mechanical ground to the chassis 320, suspending thelateral bed 332 of the force-sensitive structure 310 b within the barrel302 and/or the interior of the chassis 320 of the stylus 300. In somecases, one end of each of the front and rear cantilevered legs 334, 336is fixed with respect to the chassis 320 and the barrel 302 and thelateral bed 332 is allowed to shift or move laterally. As described inmore detail below with respect to FIGS. 4A-4M, the front and rearcantilevered legs 334, 336 may deflect and the lateral bed 332 may shiftin response to a force exerted on the nib 308 b (or movable portion 306b).

In particular, the movable portion 306 b of the point assembly 306 ofthe stylus 300 may be mechanically coupled to the rigid signal conduit310 a. In turn, the rigid signal conduit 310 a can be coupled to thelateral bed 332 of the force-sensitive structure 310 b. For example, themovable portion 306 b of the point assembly 306 can be coupled to atleast one of the rear cantilevered leg 334 or the front cantilevered leg336 and/or the lateral bed 332. In the present embodiment, the movableportion 306 b is coupled to the lateral bed 332 via the tubular shield340. In this manner, when the movable portion 306 b of the pointassembly 306 of the stylus 300 moves toward the barrel 302 and/orwithdraws into the interior of the chassis 320, the rear cantileveredleg 334 and the front cantilevered leg 336 deflect.

Upon removing the stylus 300 from the input surface (and, thus, removingthe reaction force acting on the stylus 300), one or both of the rearcantilevered leg 334 and the front cantilevered leg 336 of theforce-sensitive structure 310 b are formed from a resilient material andreturn the movable portion 306 b of the point assembly 306 of the stylus300 to its nominal position.

In many embodiments, the rear cantilevered leg 334 and the frontcantilevered leg 336 are substantially orthogonal to the lateral bed 332when in a neutral position. In other cases, the rear cantilevered leg334 and the front cantilevered leg 336 extend from the lateral bed 332at an oblique angle. In some cases, both the rear cantilevered leg 334and the front cantilevered leg 336 connect to the same side of thelateral bed 332 (for example, as illustrated). This embodiment causesthe force-sensitive structure 310 b to exhibit a profile of a widenedU-shape. In other cases, the rear cantilevered leg 334 and the frontcantilevered leg 336 connect to opposite sides of the lateral bed 332; aprofile of the force-sensitive structure 310 b takes an elongatedS-shape or Z-shape.

In these embodiments, the force-sensitive structure 310 b also includesan element that exhibits an electrically-measurable property thatchanges as a function of the magnitude of force applied. In one example,a strain-sensitive electrode 338 may be coupled to the rear cantileveredleg 334 of the force-sensitive structure 310 b. The strain-sensitiveelectrode 338 can be coupled to an electrical circuit within the stylus300. The electrical circuit can be configured to monitor one or moreelectrical properties (e.g., resistance, capacitance, accumulatedcharge, inductance, and so on) of the strain-sensitive electrode 338 forchanges. The electrical circuit then quantifies these changes which maybe used to estimate the applied force. Thereafter, the stylus 300 cancommunicate the applied force to the electronic device, which may beinterpreted as a user input.

In many embodiments, more than one strain-sensitive electrode isincluded. For example, a first strain-sensitive electrode can be coupledto a left side of the rear cantilevered leg 334 and a secondstrain-sensitive electrode can be coupled to a right side of the rearcantilevered leg 334. In other words, more than one strain-sensitiveelectrode can be arranged next to one another on the rear cantileveredleg 334. In some embodiments, one of the strain-sensitive electrodes canbe placed in compression whereas another strain-sensitive electrode isplaced into tension (e.g., tensile strain) in response to deformation ofthe rear cantilevered leg 334. In other cases, all of the more than onestrain-sensitive electrodes are placed in compression (e.g., compressivestrain) in response to deformation of the rear cantilevered leg 334.

The multiple strain-sensitive electrodes can be connected to anelectrical circuit (e.g., sensor circuitry) in order to approximate amagnitude of strain (e.g., compression or tension) experienced by therear cantilevered leg 334. In this example, a magnitude of strain can beobtained by measuring either a common property (e.g., parallel and/orseries resistance) or a differential property (e.g., voltage division)of the multiple strain-sensitive electrodes.

In one embodiment, a common property estimate such as parallelresistance can be obtained by applying a known voltage to the circuitand measuring a current through the multiple strain-sensitiveelectrodes. In another embodiment, a current can be injected into themultiple strain-sensitive electrodes and a voltage can be estimatedtherefrom. In either case, the resistance of either or both multiplestrain-sensitive electrodes can be calculated via Ohm's law and can, inturn, be correlated to an amount of strain experienced by thestrain-sensitive electrodes.

In another embodiment, multiple strain-sensitive electrodes can beelectrically coupled together such that a differential property estimate(such as voltage division) can be obtained by applying a known voltageto the circuit and measuring a voltage across a point between two ormore of the multiple strain-sensitive electrodes and a referencevoltage. In another embodiment, a current can be injected into themultiple strain-sensitive electrodes and a voltage, or more than onevoltage, can be estimated. In either case, the resistance of either orboth multiple strain-sensitive electrodes can be calculated via Ohm'slaw and can, in turn, be correlated to an amount of strain experiencedby one or more of the multiple strain-sensitive electrodes.

In many cases, differential property estimates can be combined with orcompared to common property estimates. In some examples, thedifferential property estimate and common property estimate can becombined by unweighted or weighted averaging. In other embodiments, themaximum or minimum of the two estimates can be used. In still furtherexamples, other methods of combining or deciding between the twoestimates can be used.

In other cases, an actual calculation of resistance and/or accumulatedcharge for each independent strain-sensitive electrode may not berequired. For example, in certain embodiments, an estimated voltage orcurrent (e.g., from a common property estimate, differential propertyestimate, or both) can be correlated directly to an amount of strainexperienced by the force-sensitive structure.

Once the resistance of each strain-sensitive electrode is obtained viacalculation or measurement, each can be compared to a known baselineresistance value in order to determine whether the strain-sensitiveelectrodes are experiencing tension or compression. In other words, whenthe force-sensitive structure experiences a reaction force, it maydeform, causing one or more strain-sensitive electrodes to either expand(e.g., tension) or contract (e.g., compression), which can cause theresistance thereof to change in a mathematically predictable manner. Insome cases, the resistance or other electrical property of thestrain-sensitive electrode 338 is measured as a relative value, whichmay factor environmental effects, such as temperature and/or residual orstatic strain.

For certain materials, resistance can change linearly with compressionor tension. For other materials, resistance can change following a knowncurve in response to compression or tension. Accordingly, depending uponthe material selected for the strain-sensitive electrodes, and theposition of the strain-sensitive electrodes on the force-sensitivestructure (whether on the rear cantilevered leg 334, the lateral bed332, or both), a particular resistance can be correlated to a particularamount of strain experienced by a particular strain-sensitive electrode,which in turn can itself be correlated to an amount of force applied tothe force-sensitive structure, which in turn can be correlated to anamount of force applied by the tip portion to the input surface.

As noted above, the strain-sensitive electrode 338 can be made of anynumber of suitable materials. In some examples, the strain-sensitiveelectrode 338 can be made from a number of materials arranged in alaminated stack. For example, in one embodiment, the strain-sensitiveelectrode 338 can be implemented as a capacitive sensor; twoelectrically conductive plates are separated by a dielectric material.As the capacitive electrode shifts and/or moves in response todeformation of the force-sensitive structure 310 b in response to areaction force, the capacitance exhibited by the capacitive electrodechanges. The electrical circuit can estimate these changes and correlatethe same to a magnitude of force in accordance with embodimentsdescribed herein.

Although many embodiments position the strain-sensitive electrode 338along an external surface of the rear cantilevered leg 334, thisconfiguration is not required. For example, in some embodiments, thestrain-sensitive electrode 338 can be positioned to overlap the rearcantilevered leg 334 and the lateral bed 332. In other words, thestrain-sensitive electrode 338 can extend around the corner (e.g.,interface) between the rear cantilevered leg 334 and the lateral bed332.

In still further embodiments, the strain-sensitive electrode 338 can bepositioned between the lateral bed 332 and the chassis 320. In theseembodiments, the strain-sensitive electrode 338 is partially fixed andpartially floating. More specifically, the strain-sensitive electrode338 is fixed with respect to the chassis 320, and mechanically coupledto the lateral bed 332. In this manner, when the lateral bed 332displaces within the chassis 320 (e.g., in response to a reactionforce), the strain-sensitive electrode 338 deforms.

In other embodiments, the deflection of the force-sensitive structure310 b can be measured in another manner such as with, but not limitedto: optical sensors; acoustic sensors; resonance sensors; peizoresistivesensors; and so on.

As noted above, the force-sensitive structure 310 b is in mechanicalcommunication with the movable portion 306 b of the point assembly 306via the rigid signal conduit 310 a.

The rigid signal conduit 310 a includes a tubular shield 340. Thetubular shield 340 includes a hollow portion and tray portion. Asillustrated, the hollow portion of the tubular shield 340 extendsdownwardly, and is threaded at an end thereof opposite the tray portion.The tubular shield 340 may provide electromagnetic shielding forelectrical conduit (e.g., signal lines, traces, and so on) that passesthrough the hollow portion. The tubular shield 340 may also beconfigured to provide rigid structural support to transfer reactionforces received at the point assembly 306 to the force-sensitivestructure 310 b without substantial deflection or buckling. The trayportion of the tubular shield 340 may be configured to receive, support,and partially enclose a control board 342, described in detail below(see, e.g., FIGS. 3D-3E).

The tubular shield 340 may be configured to be received within theforce-sensitive structure 310 b. More specifically, the frontcantilevered leg 336 of the force-sensitive structure 310 b defines anaperture (not visible in FIG. 3A) through which the hollow portion ofthe tubular shield 340 extends. The tray portion of the tubular shield340, together with the control board 342, is mechanically fastened tothe lateral bed 332 of the force-sensitive structure 310 b. In oneexample, the tray portion of the tubular shield 340 is fastened to thelateral bed 332 via one or more screws or other mechanical fasteningtechnique. The tubular shield 340 may be formed from a metal materialand welded to the lateral bed 332. In another example, the tray portionof the tubular shield 340 is adhered to the lateral bed 332 via apressure sensitive adhesive, a curable adhesive, or a silicone orpolymer seal. In some cases, the tray portion of the tubular shield 340is potted within the lateral bed 332. In these examples, the lateral bed332 can include sidewalls that extend upwardly from the edges of thelateral bed 332; a potting material configured to seal at least onecomponent of the tray portion of the tubular shield 340 is applied overthe tray portion, and may abut the sidewalls of the lateral bed.

In this manner, the tubular shield 340 is at least partially inset intothe force-sensitive structure 310 b. A force applied (e.g., a reactionforce, such as described above) to the threaded end of the hollowportion of the tubular shield 340 transfers to the lateral bed 332,causing the front cantilevered leg 336 and the rear cantilevered leg 334of the force-sensitive structure 310 b to deflect.

In many embodiments, the tubular shield 340 also extends through thegrounded portion 306 a of the point assembly 306. For example, thetubular shield 340 can extend through the support collar 316 and theflanged nut 318. In typical embodiments, the tubular shield 340 may beconfigured to extend through each element of the grounded portion 306 awithout impacting internal sidewalls thereof. More specifically, thetubular shield 340 is free to move within the grounded portion 306 a.

The rigid signal conduit 310 a also includes one or more load-shiftingnuts 344 attached to the threaded end of the hollow portion of thetubular shield 340. In the illustrated embodiment, two load-shiftingnuts 344 are shown, but one may appreciate that in differentembodiments, more than two load-shifting nuts 344 can be used (see,e.g., FIGS. 3D-3E). In other embodiments, a single load-shifting nut maybe included.

In the illustrated embodiment, a back load-shifting nut 344 a and afront load-shifting nut 344 b are shown. Generally and broadly, the backload-shifting nut 344 a and the front load-shifting nut 344 b areattached to the threaded end of the hollow portion of the tubular shield340, and separated by a selected distance.

The back load-shifting nut 344 a may be separated from the flanged nut318 by a distance less than the clearance gap 312. Similarly, the frontload-shifting nut 344 b may be configured to abut the collar 308 a ofthe nosepiece 308 to ensure that the nosepiece 308 may not undesirablyseparate from the rigid signal conduit 310 a.

The back load-shifting nut 344 a is separated from the flanged nut 318in order to control the peak mechanical load transferred to theforce-sensitive structure 310 b or, more generally, other electrical ormechanical components disposed within the barrel 302. More specifically,the back load-shifting nut 344 a may be configured to impact the flangednut 318 during the closure of the clearance gap 312 (e.g., a reactionforce is received, causing the movable portion 306 b to move toward thebarrel 302). The distance separating the back load-shifting nut 344 aand the flanged nut 318 may be configurable or fixed.

The rigid signal conduit 310 a also includes a core insert 346. A bulkof the core insert 346 is formed from an electrically insulatingmaterial, such as plastic. For increased rigidity, the bulk of the coreinsert 346 can be doped with a fiber material, such as glass fiber.

The core insert 346 defines several signal paths therethrough. In oneexample, the core insert 346 defines two distinct signal paths, one thatmay be configured to convey the tip signal to the tip-field generator314, and one that may be configured to convey the ring signal to aring-field generator 348 (described in detail below).

The core insert 346 can also include one or more grounding shields. Thegrounding shields can provide electromagnetic isolation between thesignal paths configured to convey the tip signal and the ring signal.For example, in some embodiments, a ground shield of the core insert 346can be disposed between a ring signal path and a tip signal path. Inother cases, one or more grounding shields can enclose the ring signalpath and the tip signal path in order to prevent external interferencefrom affecting the same.

The core insert 346 includes a body 350 and a flexible circuit 352. Thebody 350 of the core insert 346 may be configured to be inserted withinthe tubular shield 340. In this manner, the tubular shield 340 provideselectromagnetic shielding to signal paths traversing the length of thebody 350.

The flexible circuit 352 of the core insert 346 may be configured tocouple to the control board 342. In one example, the control board 342is soldered to the flexible circuit 352. In other cases, a hot barcoupling technique can be used.

The control board 342 can include connectors, solder/hot bar pads,circuitry, processors, and traces and/or system bus lines connecting thesame. These components can be affixed using any suitable mountingtechnique to a flexible substrate, rigid substrate, or a flexiblesubstrate that is coupled to a stiffener. The control board 342 caninclude more than one circuit board connected by a flexible connector.In this embodiment, the control board 342 can be folded over itself orover another component of the stylus.

As noted above, the core insert 346 includes a signal line dedicated toconveying the tip signal to the tip-field generator 314 (herein, the“tip signal line”) and another signal line dedicated to conveying thering signal to the ring-field generator 348 (herein, the “ring signalline”). While these are described as a single line, the tip signal lineand ring signal line may each be made from multiple individualconductive elements, lines, or traces.

In one example, the tip signal line (not visible in FIG. 3A) terminatesin a contact pad 354 at a bottom end of the core insert 346. In oneexample, the contact pad 354 is formed during the manufacturing processof the core insert 346. For example, flashing of the core insert 346 canbe cut in a finishing process. The location of the cut may beintentionally selected so as to expose the tip signal line. In somecases, the cut can be serrated in order to increase the surface area ofthe exposed signal line; the increased surface area can bond and/orsolder to the contact pad 354 in a more durable manner.

In these embodiments, the contact pad 354 can couple to the tip-fieldgenerator 314 in any electrically-suitable manner. For example, as notedabove, the tip-field generator 314 may be partially flexible, forexample, when implemented as a pogo pin. In another example, the contactpad 354 can be soldered to the tip-field generator 314. In still furtherexamples, the tip-field generator 314 can sit within an electricallyconductive paste that is applied to the contact pad 354 in amanufacturing step.

In still further examples, the contact pad 354 can be partiallyflexible. For example, the contact pad 354 can be formed from anelectrically conductive foam or elastomer. In other cases, the contactpad 354 can include pogo pin geometry in addition to and/or separatefrom pogo pin geometry of the tip-field generator 314.

As noted with respect to other embodiments described herein (and asillustrated), the tip-field generator 314 and the ring-field generator348 are co-axially aligned along the length of the core insert 346 sothat the fields generated thereby (e.g., the tip field and the ringfield) are axially symmetrical. In this manner, a user can grasp andhold the stylus 300 in any manner that is comfortable to the user.

The ring-field generator 348 takes the shape of a closed ring throughwhich the tip signal line passes. In addition, one or more groundinglayers, sheaths, or other structures can enclose the tip signal linewithin the ring-field generator 348. In this manner, the ring-fieldgenerator 348 may not interfere with the tip signal, and both the ringfield and the tip field may be substantially spherical and coaxiallyaligned.

The ring-field generator 348 can be formed in any suitable manner. Inmany cases, many examples (and as illustrated), the ring-field generator348 is around (and/or partially within) the core insert 346. Forexample, the ring-field generator 348 is formed on an external surfaceof the core insert 346. The ring-field generator 348 can be disposedonto the external surface of the core insert 346 using any number ofsuitable manufacturing techniques, including, but notlimited to:physical vapor deposition, pulsed laser deposition, self-adheringconductive film, metallic leafing techniques, metallic platingtechniques, and so on. In other cases, the ring-field generator 348 maybe a solid metal ring that is insert-molded into the core insert 346.

The ring-field generator 348 can be formed from any number of suitableelectrically conductive materials. In some examples, the ring-fieldgenerator 348 is formed from metal. In other cases, the ring-fieldgenerator 348 is formed from a deposited electrically conductivematerial, such as a metal-oxide or a metal powder. For example, theelectrically conductive material can be deposited via pulsed laserdeposition, physical vapor deposition, or any other suitable technique.

In some cases, the ring-field generator 348 is formed from a singlematerial, whereas in other cases the ring-field generator 348 is formedfrom more than one material. In some cases, the ring-field generator 348is rigid, whereas in other cases the ring-field generator 348 may be atleast partially compliant and/or flexible.

The ring-field generator 348 may be coupled to the ring signal line inany electrically suitable manner. In one example, a via through the coreinsert 346 connects the ring signal line to the ring-field generator348.

As noted above, the ring-field generator 348 may be configured togenerate an electric field (e.g., the ring field) that is approximatelyspherical in nature when estimated from a particular distance. In otherwords, the ring-field generator 348 may function, substantially, as afield source that takes a ring shape (e.g., an annular shape); the fieldgenerated by a ring-shaped field source is substantially spherical ifmeasured from a distance greater than the radius of the ring. Thus, inmany embodiments, the radius of the ring-field generator 348 is smallerthan the distance separating the center of the ring-field generator 348and the tip of the nib 308 b.

The individual components of the stylus 300 described above and depictedin FIG. 3A generally and broadly relate to the coordination engine 206described with respect to FIG. 2D. The various components, connections,and placements of these components may vary substantially fromembodiment to embodiment; the depicted elements present merely oneexample and certain components may be substituted or omitted in certainimplementations.

Next, reference is made to certain operational components of the stylus300 that may be disposed within the chassis 320. Particularly, thestylus 300 may include a processing unit circuit board set 356.

The processing unit circuit board set 356 may include one or moresubstrates on or through which one or more electronic components aredisposed. These components may be surface mount or through-holecomponents. Components may be attached to both sides of the substrate.The substrate can be a single layer circuit board, a multi-layer circuitboard, or a flexible circuit board. In some examples, a flexible circuitboard can be used that is made rigid with one or more stiffeners.

In the illustrated embodiment, the processing unit circuit board set 356includes substrates that are connected by one or more flexible circuits.A top control board 358 may be coupled to a bottom control board 360 viaone or more flexible connectors 362. In some cases, the flexibleconnectors 362 are formed integrally with either or both the top controlboard 358 and/or the bottom control board 360. In these embodiments, theflexible connectors 362 electrically and mechanically couple the topcontrol board 358 to the bottom control board 360 without the need for aseparate mechanism, coupling, connector, or manufacturing step toconnect the same.

However, in other embodiments, the flexible connectors 362 can beseparate from the top control board 358 and/or the bottom control board360. For example, the flexible connectors 362 are permanently orremovably attached to either or both the top control board 358 and/orthe bottom control board 360.

In many cases, the top control board 358 and the bottom control board360 take substantially the same shape. In this manner, the bottomcontrol board 360 can be folded underneath the top control board 358(shown in the illustrated embodiment as a fold path 364). Thereafter,the top control board 358 and the bottom control board 360 can befastened together in a manner that retains a selected distance betweenthe boards. In some embodiments, the top control board 358 and thebottom control board 360 can be folded over other components of thestylus 300.

In one embodiment, the top control board 358 and the bottom controlboard 360 can be fastened together with a first standoff 366, a secondstandoff 368, and a spacer 370. The first standoff 366 and the secondstandoff 368 may be disposed at a top edge and a bottom edge of thefolded boards, respectively. The spacer 370 may be positioned generallyin the middle of the top control board 358 and the bottom control board360.

The first standoff 366 and the second standoff 368 can be fastened tothe boards via one or more mechanical fasteners, such as screws. Inother cases, the first standoff 366 and the second standoff 368 areadhered to the boards using an adhesive. In some cases, the firststandoff 366 and/or the second standoff 368 can be electricallyconnected to a circuit ground of either or both boards.

The width of the processing unit circuit board set 356, when folded, isselected to be less than the internal diameter of the chassis 320. Inthis manner, the processing unit circuit board set 356 can be disposedwithin the chassis 320 during manufacturing. In many embodiments, theprocessing unit circuit board set 356 is positioned within a middleportion of the chassis 320, adjacent to the assembly window 326. In thismanner, during assembly, at least a portion of the processing unitcircuit board set 356 can be accessed through the assembly window 326(see, e.g., FIGS. 3D-3F).

The processing unit circuit board set 356 couples to the control board342 of the coordination engine 310 so data, signals, and/or power can beexchanged between them. In one embodiment, a flexible circuit 372 can beused to couple the processing unit circuit board set 356 to the controlboard 342 of the coordination engine 310. The processing unit circuitboard set 356 may be configured to, without limitation, at least one ofthe following: provide power and/or circuit ground connections to thecontrol board 342; provide the tip signal and/or ring signal to thecontrol board 342; provide parameters to the control board 342 that thecontrol board 342 uses to generate the tip signal and/or ring signal;provide data to the control board 342 for the control board 342 tomodulate into the tip signal and/or ring signal; receive from thecontrol board 342 a force measurement; and so on.

Similarly, the control board 342 may be configured to, withoutlimitation, at least one of the following: receive power and/or circuitground connections from the processing unit circuit board set 356;receive a tip signal and/or a ring signal from the processing unitcircuit board set 356; receive parameters related to a tip signal and/orring signal from the processing unit circuit board set 356; generate atip signal and/or ring signal in accordance with the parameters; measurean electrical property of the strain-sensitive electrode 338; determinea force associated with an electrical property of the strain-sensitiveelectrode 338; provide to the processing unit circuit board set 356 anestimation of force; and so on.

The control board 342 can include any number of suitable circuits orcircuitry. For example, in many embodiments, the control board 342 canbe configured to convey the tip signal and the ring signal to thetip-field generator 314 and the ring-field generator 348, respectively.In other cases, the control board 342 can be configured to estimate oneor more electrical properties of the strain-sensitive electrode 338and/or associate the magnitudes of such electrical properties to amagnitude of force received by the force-sensitive structure 310 b. Thecontrol board 342 can communicate with the processing unit circuit boardset 356. For example, the processing unit circuit board set 356 mayconvey to the control board 342 stylus identity information, useridentity information, or stylus setting information. The control board342 can receive this information and modify the tip signal and/or thering signal accordingly. In other examples, the control board 342receives the tip signal and/or the ring signal directly from theprocessing unit circuit board set 356.

In one example, the flexible circuit 372 includes a connector 374 thatmay be configured to connect to a port 376 of the processing unitcircuit board set 356. Additionally, the flexible circuit 372 includesone or more hot bar pads 378 that are configured to be permanentlycoupled to the control board 342. In other cases, the flexible circuit372 can connect to the control board 342 using a connector such as theconnector 374 (see, e.g., FIGS. 3D-3F).

In addition to coupling the control board 342 of the coordination engine310 to the processing unit circuit board set 356, the flexible circuit372 can also couple the strain-sensitive electrode 338 (or more than oneelectrode) of the force-sensitive structure 310 b to either or both thecontrol board 342 or the main control board 365. The connection betweenthe flexible circuit 372 and the strain-sensitive electrode 338 can bepermanent or removable; the connection can be a soldered connection, ahot barred connection, or a connection made between a connector and aport.

The flexible circuit 372 can also include an articulated portion 382.The articulated portion 382 permits the flexible circuit 372 to contractor fold when a reaction force causes the electromechanical coupling toshift. Generally, the flexible circuit 372 allows for the relativemotion of the force-sensitive structure 310 b with respect to theprocessing unit circuit board set 356. The shape of the articulatedportion 382 may reduce or minimize effects of the electrical connectionbetween the control board 342 and the processing unit circuit board set356. In some embodiments, the articulated portion 382 is configured toreduce the relax time or time constant of the force-sensitive structure310 b after a deflection or force-sensing event.

The processing unit circuit board set 356 is also coupled to a batterypack 384. The battery pack 384 may be a lithium-polymer battery pack ora lithium ion battery. However, in other embodiments, alkalinebatteries, nickel-cadmium batteries, nickel-metal hydride batteries, orany other suitable rechargeable or one-time-use batteries may be used.

For embodiments in which the battery pack 384 is a lithium-polymerbattery pack, the battery pack 384 may include stacked layers that mayform the components of the battery pack 384 (e.g., anode, cathode). Inmany embodiments, the battery pack 384 may be folded or rolled prior tobeing sealed in a pouch (not shown). In some embodiments, the pouch maybe a rectangular pouch that may be rolled or folded after the batterypack 384 is inserted therein. The direction of the rolls or folds may begenerally aligned with the longitudinal axis of the barrel 302. In thismanner, the battery pack 384 may have little or no unused space whenpositioned within the chassis 320.

In some embodiments, the battery pack 384 may include one or more othercomponents, such as flow barriers and/or encapsulation walls operablyconnected to either or both the cathode electrode collector and theanode electrode collector, among other components.

The particular configuration of battery pack 384 described above ismerely a simplified example, and the number and order of the individualcomponents may vary. In many examples, the battery pack 384 includes oneor more leads 386 that are configured to permanently or removably attachto the processing unit circuit board set 356. The battery pack 384includes a power control board 388. The battery pack 384 and the powercontrol board 388 are sized so as to fit within the chassis 320. In somecases, the battery pack 384 may be axially aligned with a central axisof the chassis 320, although this is not required of all embodiments. Insome cases, the battery pack 384 may be axially offset with respect to acentral axis of the chassis 320. In these embodiments, the offsetalignment of the battery pack 384 may cause the stylus 300 to beeccentrically balanced along its longitudinal axis which, in turn, mayprevent the stylus 300 from rolling when the stylus 300 is placed on asurface. In some embodiments, marking on the exterior of the stylus 300such as instructions, logos, personalization, icons, and so forth may bepositioned based on the alignment of the battery pack 384 so that themarkings may be either visible or hidden when the stylus 300 is placedon a surface.

The power control board 388 includes circuitry configured to control thecharge and/or discharge rate of the battery pack 384. In many examples,the power control board 388 is communicably coupled directly to theprocessing unit circuit board set 356 via a signal path trace thatextends along the length of the battery pack 384 (see, e.g., FIGS.3D-3F).

In some cases, the power control board 388 and/or another portion of thebattery pack 384 can be disposed (at least partially) within theinternal volume of the antenna support block 324 b. In some cases, leadsextending from the power control board 388 can be intentionallylengthened into a service loop. The service loop can be included tosimplify manufacturing of the stylus 300.

The power control board 388 can include connectors, solder/hot bar pads,circuitry, processors, and traces and/or system bus lines connecting thesame. These components can be affixed using any suitable mountingtechnique to a flexible substrate, rigid substrate, or a flexiblesubstrate that is coupled to a stiffener. The power control board 388can include more than one circuit board connected by a flexibleconnector. In this embodiment, the power control board 388 can be foldedover itself or over another component of the stylus, in a manner similarto the processing unit circuit board set 356.

In many examples, the power control board 388 is configured to, withoutlimitation, at least one of the following: provide information relatedto the capacity of the battery pack 384 to the processing unit circuitboard set 356; provide information related to the charging speed of thebattery pack 384 to the processing unit circuit board set 356; provideinformation related to the age, health, or expansion of the battery pack384 to the processing unit circuit board set 356; and so on.

In many cases, the battery pack 384 can be disposed such that the massof the battery pack 384 is coaxially aligned with the length of thestylus 300.

The stylus 300 also includes a data and/or power connector 390. The dataand/or power connector 390 may be coupled to both the power controlboard 388 and the processing unit circuit board set 356. The data and/orpower connector 390 includes a connector end 392 and a plug collar 394.

The connector end 392 can be configured to couple to a power and/or dataport of an electronic device to facilitate recharging of the batterypack 384. In other cases, the connector end 392 can be used to exchangedata between the stylus 300 and an electronic device. The connector end392 can be configured to be flexible (laterally moveable within the plugcollar 394) so that when connected to an electronic device, the stylus300 can resist and withstand certain forces that may otherwise damagethe stylus 300 and/or the electronic device.

Although the connector end 392 is illustrated as a multi-pin,reversible, and standardized data and/or power connector, it isappreciated that such a connector is not required. Particularly, in someembodiments, a Lightning connector, Universal Serial Bus connector,Firewire connector, serial connector, Thunderbolt connector, headphoneconnector, or any other suitable connector can be used.

In some cases, the data and/or power connector 390 can be disposed (atleast partially) within the internal volume of the antenna support block324 b. In some cases, one or more leads 390 a extending from the dataand/or power connector 390 can be intentionally lengthened into aservice loop. The service loop can be included to simplify manufacturingof the stylus 300.

In many cases, the blind cap 304 may be configured to conceal a dataand/or power connector 390 of the stylus 300. The data and/or powerconnector 390 may be concealed by the blind cap 304 (see, e.g., FIG. 3Dand FIG. 3F).

As illustrated, the data and/or power connector 390 may extend outwardlyfrom the barrel 302 when assembled. The plug collar 394 can beconfigured to seal the barrel 302 when assembled. In some embodiments,the data and/or power connector 390 can retract, either manually orautomatically, and either partially or entirely, into the barrel 302when not in use. In some examples, the data and/or power connector 390can be connected to a push-push mechanism.

The processing unit circuit board set 356 is also coupled to the antennaassembly 324. The antenna assembly 324 includes an antenna 324 a, anantenna support block 324 b, a transmission line 324 c, and a connector324 d. The antenna 324 a is disposed onto or otherwise coupled to theantenna support block 324 b. In some embodiments, the antenna supportblock 324 b is formed from a dielectric material, such as plastic. Theantenna 324 a can be disposed onto the external surface of the antennasupport block 324 b using any number of suitable manufacturingtechniques, including, but notlimited to: physical vapor deposition,pulsed laser deposition, self-adhering conductive film, metallic leafingtechniques, metallic plating techniques, and so on. In some embodiments,the antenna 324 a is formed using a laser direct structuring techniqueand formed directly on the outer surface of the antenna support block324 b.

The antenna support block 324 b defines an internal volume. The internalvolume of the antenna support block 324 b can be sized and/or otherwiseconfigured to retain other components of the stylus 300 such as, but notlimited to: electronic circuits, batteries, sensors, service loops ofwire, flexible connectors, ground planes, balancing weights, flexibleelements, moisture detection features, and so on.

The connector 324 d may be configured to directly connect to a connectoron the processing unit circuit board set 356. In many cases, theconnector 324 d and the transmission line 324 c may be shielded so thatsignals passing therethrough are not affected by external interferenceand, oppositely, the signals passing therethrough do not affect anycomponents within the stylus 300.

The transmission line 324 c may be configured to run alongside oradjacent to the battery pack 384 when the antenna assembly 324 and thebattery pack 384 are assembled within the chassis 320. The transmissionline 324 c is generally aligned to be parallel to the longitudinal axisof the barrel 302. As noted above, the antenna assembly 324 is insertedinto the chassis 320 so that the antenna 324 a aligns with the antennawindow 322.

In some cases, the transmission line 324 c can be separated from aninner surface of the chassis 320 by a compressible element 396. Thecompressible element 396 includes a compressible foam 396 a, and one ormore binding elements 396 b. The binding elements 396 b can attach thecompressible foam 396 a and the transmission line 324 c to the batterypack 384.

As noted with respect to many embodiments described above, many of thecomponents of the stylus 300 may be disposed, at least partially, withinthe chassis 320. In this manner, the chassis 320 provides effectiveelectromagnetic shielding to a number of the elements of the stylus 300.

To facilitate installation of the various components within the chassis320, said components may, in some examples, be attached to a sled 398.The sled 398, along with all components it contains, may be slid intothe chassis 320. Thereafter, the chassis 320 and the sled 398 can befastened to one another in any suitable manner. For example, screws,rivets, or adhesive can be used to fasten the chassis 320 to the sled398. In other examples, the chassis 320 can be welded to the sled 398.The chassis 320 may then be inserted into the internal volume of thebarrel 302 (see, e.g., FIGS. 3D-3F).

In some cases, the sled 398 can serve as a system ground, proving anelectrical ground for all (or substantially all) the electrical circuitsdisposed within the stylus 300. In other cases, the sled 398 can alsoserve as a ground plane for one or more antenna elements.

The foregoing description of the embodiments depicted in FIGS. 3A-3B,and various alternatives and variations, are presented, generally, forpurposes of explanation, and to facilitate a thorough understanding of astylus as contemplated herein. However, it will be apparent to oneskilled in the art that some of the specific details presented hereinmay not be required in order to practice a particular describedembodiment, or an equivalent thereof.

Thus, the foregoing and following descriptions of specific embodimentsare understood to be presented for the limited purposes of illustrationand description. These descriptions are not targeted to be exhaustive orto limit the disclosure to the precise forms recited herein. To thecontrary, it will be apparent to one of ordinary skill in the art thatmany modifications and variations are possible in view of the aboveteachings. Particularly, it may be understood that the stylus depictedin FIGS. 3A-3B can be implemented in a number of suitable andimplementation-specific ways.

Generally and broadly, FIGS. 4A-4M reference different embodiments of acoordination engine of a stylus such as described herein. A user maymanipulate the stylus and apply a force to an input surface of anelectronic device. A corresponding reaction force may be transferredthrough the tip of the stylus connected to the electromechanicalcoupling and to a force-sensitive structure positioned within thestylus. The force-sensitive structure may deform in response which maybe measured by the stylus and used to estimate the applied force. Theforce-sensitive structures described with respect to FIGS. 4A-4M may beused to produce a non-binary output that corresponds to the appliedforce. For example, the force-sensitive structures may be used toproduce an output that represents a magnitude that varies in accordancewith a variable amount of applied force.

FIG. 4A depicts a side view of a coordination engine 400 of a stylus,particularly showing a force-sensitive structure that supports a tip ofthe stylus. As with the embodiment described with respect to FIG. 3A,the coordination engine 400 includes a tubular shield 402 that enclosesa rigid conduit 404 configured to convey electrical signals receivedfrom a control board 406 via one or more signal paths (e.g., the tipsignal path and the ring signal path) to a nosepiece 408 of the stylus.The nosepiece 408 includes a collar 410 that is threaded onto acorrespondingly-threaded portion of the tubular shield 402 which, inturn, may be mechanically coupled to a force-sensitive structure 412.The nosepiece 408 may be removed from the force-sensitive structure 412and treated as a disposable, substitutable, or replaceable component.

The tubular shield 402 and the control board 406 are mechanicallycoupled to a force-sensitive structure 412 with any suitable method. Thetubular shield 402 includes a hollow portion and a bed portion. Thetubular shield 402 is formed from an electrically conductive materialhaving a rigidity that prevents the tubular shield 402 from buckling ordeflecting when a force is applied. The length of the hollow portion ofthe tubular shield 402 may be selected so as to provide electromagneticshielding to a tip-field generator (not shown) or a ring-fieldgenerator.

The force-sensitive structure 412 can be described, generally, as acantilevered sled that can move inwardly with respect to the body of astylus in response to a force. The cantilevered portions of theforce-sensitive structure 412 are affixed, at one end, to an internalstructure of the stylus, such as the chassis 320 depicted in FIG. 3A.

The force-sensitive structure 412 includes a front cantilevered leg 414and rear cantilevered leg 416 that are coupled together or joined by alateral bed 418 that extends between the two cantilevered legs. As notedwith respect to other embodiments described herein, the frontcantilevered leg 414 and the rear cantilevered leg 416 are fixed withrespect to the body of the stylus (e.g., the barrel as shown in FIG.3A). In this example, the combined shape of the front cantilevered leg414, the lateral bed 418, and the rear cantilevered leg 416 form anelongated U-shape. A strain-sensitive electrode 420 is positioned on aback surface of the rear cantilevered leg 416.

The force-sensitive structure 412 may be formed from a resilient orcompliant material that is configured to deflect or bend withoutyielding or breaking; in some embodiments, the force-sensitive structure412 is formed from a tempered spring steel that is configured to deflectin a predictable and repeatable manner. The force-sensitive structure412 may also be molded from a polymer material, formed from a compositeof polymer and metal, or other combination of materials.

The front and rear cantilevered legs 414, 416 may be fixed to one ormore internal components of the stylus. In some implementations, thelegs are welded to a sleeve or chassis using a laser-welding or otherprecision welding process. The legs may also be fixed using a mechanicaltab, fastener, or other mechanical attachment technique.

In this manner, when the nosepiece 408 of the stylus applies a forceF_(a) to an input surface 422, and an equal and opposite reaction forceF_(r) is conveyed to the electromechanical coupling by the nosepiece408, it causes the nosepiece 408 to partially withdraw or deflectinward, in turn causing the front cantilevered leg 414 and the rearcantilevered leg 416 to deflect or deform along a serpentine curve, suchas shown in FIG. 4B. The strain-sensitive electrode 420 is deformed as aresult of the deformation of the rear cantilevered leg 416. Thedeformation of the strain-sensitive electrode 420 can be measured by anelectrical circuit in order to determine the magnitude of the reactionforce F_(r). As described in more detail below with respect to FIGS. 4Cand 4K-4M multiple strain-sensitive electrodes may be disposed on one ormore surfaces of the rear cantilevered leg 416.

Typically, the front cantilevered leg 414 and the rear cantilevered leg416 deform in an S-shape (such as shown), although this is not requiredand other deformations are possible for different embodiments. Thedeflection of the rear cantilevered leg 416 may also be described as aserpentine shape having a concave region, a convex region, and aninflection region (e.g., zero or near-zero strain point) joining theregions. In some embodiments the lateral bed 418 can include one or morestiffeners 424, as shown in the cross-section depicted in FIG. 4D, takenalong line A-A of FIG. 4A. The stiffeners 424 can be applied and/oradhered to one or more sides of the lateral bed 418. The stiffeners 424provide structural support to the lateral bed 418 so that theforce-sensitive structure 412 deforms substantially only at thegrounding point of the front cantilevered leg 414 and the rearcantilevered leg 416. In other words, the stiffeners 424 cause thelateral bed 418 to remain substantially parallel to inner sidewalls(e.g., inner portions) of the barrel of the stylus and/or a chassis ofthe stylus. In these embodiments, the force-sensitive structure 412takes the general shape of a box when no force is applied and takes thegeneral shape of a parallelogram (with or without deformed sides) when aforce is applied.

As illustrated in FIG. 4C, a first strain-sensitive electrode 420 a isdisposed on an upper portion 416 a of the rear cantilevered leg 416 anda second strain-sensitive electrode 420 b is disposed on a lower portion416 b of the rear cantilevered leg 416. An inflection point 416 c isbetween the upper portion 416 a and the lower portion 416 b. In thismanner, the first strain-sensitive electrode 420 a experiencescompression (e.g., the upper portion 416 a is concave) when the rearcantilevered leg 416 deforms whereas the second strain-sensitiveelectrode 420 b experiences tension (e.g., the lower portion 416 b isconvex) when the rear cantilevered leg 416 deforms.

In some embodiments the lateral bed 418 can include one or morestiffeners 424, such as shown in the cross-section depicted in FIG. 4D,taken along line A-A of FIG. 4A. The stiffeners 424 can be appliedand/or adhered to one or more sides of the lateral bed 418. Thestiffeners 424 provide structural support to the lateral bed 418 so thatthe force-sensitive structure 412 deforms substantially only at thegrounding point of the front cantilevered leg 414 and the rearcantilevered leg 416.

As noted with respect to other embodiments described herein, more thanone strain-sensitive electrode can be included. In some examples, astrain-sensitive electrode 420 can be applied or otherwise adhered to aninternal surface of the rear cantilevered leg 416. In still otherembodiments, a strain-sensitive electrode 420 can be applied to a frontor rear surface of the front cantilevered leg 414.

As noted with respect to other embodiments described herein, theforce-sensitive structure 412 may not necessarily take the shape asdepicted in FIG. 4A. In general, the force-sensitive structure 412 maybe characterized as having at least one cantilevered leg having one edgefixed with respect to the body or other internal structure of thestylus. The non-fixed end of the cantilevered leg may be connected orattached to a bed that is configured to shift laterally with respect tothe body or other structure of the stylus. Various non-limiting examplesof this general concept are described below with respect to FIGS. 4E-4J.

For example, in one embodiment such as depicted in FIG. 4E, theforce-sensitive structure 412 includes a front cantilevered leg 414 anda rear cantilevered leg 416 that extend from opposite sides of thelateral bed 418 and are coupled to opposite sides of the body of thestylus (e.g., the barrel as shown in FIG. 3A). In this embodiment, theforce-sensitive structure 412 takes the shape that resembles the letterZ or a letter S.

In another embodiment such as depicted in FIG. 4F, the force-sensitivestructure 412 includes a front cantilevered leg 414 and a rearcantilevered leg 416. Each includes two ends that are fixed with respectto opposite sides the body of the stylus (e.g., the barrel as shown inFIG. 3A). In this example, the front cantilevered leg 414 and rearcantilevered leg 416 extend from both sides of the lateral bed 418 andresembles the shape of an elongated letter H.

In another embodiment such as depicted in FIG. 4G, the force-sensitivestructure 412 includes a rear cantilevered leg 416 including two endswhich extend from opposite sides of the lateral bed 418 that are fixedwith respect to opposite sides of the body of the stylus (e.g., thebarrel as shown in FIG. 3A). In this embodiment, the force-sensitivestructure 412 resembles the shape of an elongated letter T, rotatedclockwise by ninety degrees.

In yet another embodiment such as depicted in FIG. 4H, theforce-sensitive structure 412 includes a rear cantilevered leg 416including one end that is fixed with respect to the body of the stylus(e.g., the barrel as shown in FIG. 3A). The unfixed end of rearcantilevered leg 416 is attached to a lateral bed 418 and has a shapethat resembles an elongated letter L, rotated counterclockwise by ninetydegrees.

In yet another embodiment such as depicted in FIG. 4I, theforce-sensitive structure 412 includes a rear cantilevered leg 416 thattakes the shape of an arc and extends in two directions at the end ofthe lateral bed 418. Both ends of the arc can be fixed with respect tothe body of the stylus (e.g., the barrel as shown in FIG. 3A). While therear cantilevered leg 416 is depicted as being convex in shape (asviewed from the tip-end of the stylus), the rear cantilevered leg 416may also be concave or have another contoured shape.

In yet another embodiment such as depicted in FIG. 4J, theforce-sensitive structure 412 is coupled to a compressible member 426.In one example, the compressible member 426 may be formed from anynumber of materials that are configured to elastically orviscoelastically deform. In this embodiment, the compressible member 426may be coupled at one or more than one location to the body of thestylus.

The foregoing description of the embodiments depicted in FIGS. 4A-4J,and various alternatives and variations, are presented, generally, forpurposes of explanation, and to facilitate a general understanding of aforce-sensitive structure and coordination engines as described withrespect to stylus embodiments disclosed herein. However, it will beapparent to one skilled in the art that some of the specific detailspresented herein may not be required in order to practice a particulardescribed embodiment, or an equivalent thereof.

Thus, the foregoing and following descriptions of these specificembodiments are understood to be presented for the limited purposes ofillustration and description. These descriptions are not targeted to beexhaustive or to limit the disclosure to the precise forms recitedherein. To the contrary, it will be apparent to one of ordinary skill inthe art that many modifications and variations are possible in view ofthe above teachings. Particularly, it may be understood that theforce-sensitive structures and coordination engines depicted in FIGS.4A-4J can be implemented in a number of suitable andimplementation-specific ways. For example, as noted above, strainsensors or, more broadly, strain-responsive elements as described hereincan be applied to one or more cantilevered legs of a force-sensitivestructure in any number of suitable ways.

Accordingly, generally and broadly, FIGS. 4K-4M depict back views of aforce-sensitive structure such as may be attached to the coordinationengine of FIG. 4A, viewed along line B-B of FIG. 4A.

FIG. 4K depicts a back surface of the rear cantilevered leg 416 of theforce-sensitive structure 412. The back surface of the rear cantileveredleg 416 can be a solid sheet of material or can define one or morecutouts. As depicted, the back surface of the rear cantilevered leg 416includes a U-shaped cutout or relief. In these embodiments, the cutoutand/or the shape of the back surface of the rear cantilevered leg 416can depend upon the amount of force sensitivity required or desired fora particular embodiment. Portions of the cantilevered leg may be thinnedor thickened to provide more or less sensitivity. Portions of thecantilevered leg may also be shaped to provide a particular shapeddeflection. For example, the cantilevered leg may have a shape orinclude features that provide an inflection point or line along thelength of the cantilevered leg while deflected. In general, thedimensions and shape of the profile of the rear cantilevered leg 416will be adapted to provide a particular responsiveness to an appliedforce. In the illustrated embodiment, it may be understood that an upperportion of the rear cantilevered leg 416 is configured to bemechanically coupled to the body of the stylus. In many cases, thisportion can be welded to a chassis of the stylus.

The back surface of the rear cantilevered leg 416 can be used to attachone or more strain-sensitive electrodes 420. In the illustratedembodiment, two strain-sensitive electrodes 420 are included. Onestrain-sensitive electrode 420 is disposed on a right side of the rearcantilevered leg 416 and one strain-sensitive electrodes 420 is disposedon a left side of the rear cantilevered leg 416.

The strain-sensitive electrodes 420 can be axially aligned, such asshown, although this may not be required or preferred for allembodiments. For example, one of the two strain-sensitive electrodes 420may be positioned more adjacent to the upper portion of the rearcantilevered leg 416.

In further embodiments, more than two strain-sensitive electrodes can beincluded. For example, FIG. 4L depicts an embodiment including fourindependent strain-sensitive electrodes 420. In still furtherembodiments, more than four strain-sensitive electrodes can be included.For example, FIG. 4M depicts an embodiment including six independentstrain-sensitive electrodes 420.

In some embodiments, one or more pairs of strain-sensitive electrodesmay be positioned on different portions of the surface of the rearcantilevered leg 416 that are placed in compressive and tensile strainmodes, respectively. As described above with respect to FIG. 4B, therear cantilevered leg 416 may deflect in an S-shaped or serpentinemanner in response to an applied force. One strain sensitive electrodeof the pair may be attached to a region of the surface that isconfigured to deflect into a compressive strain mode, and the otherstrain-sensitive electrode of the pair may be attached to a differentregion that is configured to deflect into a tensile strain mode. In somecases, the pair of strain-sensitive electrodes is positioned on oppositesides of an inflection point or inflection line that corresponds to atransition between a concave and convex contour in the deflectedsurface. Measuring a difference in the electrical response between theelectrodes in the tensile and compressive strain modes may increase thesensitivity of the deflection measurement and, therefore, increase theability of the stylus to resolve small changes in the applied force.

Suitable materials for the strain-sensitive electrodes vary fromembodiment to embodiment and may include nickel, Constantan and Karmaalloys, gallium-doped zinc oxide, polyethylenedioxythiophene, indium tinoxide, carbon nanotubes, graphene, silver nanowire, nickel nanowires,other metallic nanowires, and the like. Typically, when the electrode isstrained, such as when the tip of the stylus applies a force to theinput surface, the resistance of the electrode changes as a function ofthe strain. The resistance can be estimated with an electrical circuit.

In certain embodiments, the strain-sensitive electrodes may be estimatedby using a Wheatstone bridge. In such an example, a voltage V_(g) may beestimated across the output of two parallel voltage dividers connectedto a voltage supply V_(s). One of the voltage dividers may include tworesistors of known resistance R₁ and R₂ and the other voltage dividermay include one resistor or known resistance R₃ and the electrode Rx. Bycomparing the voltage across the output of each voltage to the voltageof the voltage supply Vs, the unknown resistance Rx of the electrode maybe calculated and, thus, the magnitude of the force applied by the tipof the stylus to the input surface can be estimated.

In another embodiment, more than one strain-sensitive electrode can bearranged next to one another on the back cantilevered leg. The multiplestrain-sensitive electrodes can be connected to an electrical circuit inorder to approximate a magnitude of strain (e.g., compression ortension) experienced by the back cantilevered leg. In this example, amagnitude of strain can be obtained by measuring either a commonproperty (e.g., parallel and/or series resistance) or a differentialproperty (e.g., voltage division) of the multiple strain-sensitiveelectrodes.

In one embodiment, a common property estimate such as parallelresistance can be obtained by applying a known voltage to the circuitand measuring a current through the multiple strain-sensitiveelectrodes. In another embodiment, a current can be injected into themultiple strain-sensitive electrodes and a voltage can be estimatedtherefrom. In either case, the resistance of either or both multiplestrain-sensitive electrodes can be calculated via Ohm's law and can, inturn, be correlated to an amount of strain experienced by thestrain-sensitive electrodes.

In another embodiment, multiple strain-sensitive electrodes can beelectrically coupled together such that a differential property estimate(such as voltage division) can be obtained by applying a known voltageto the circuit and measuring a voltage across a point between two ormore of the multiple strain-sensitive electrodes and a referencevoltage. In another embodiment, a current can be injected into themultiple strain-sensitive electrodes and a voltage, or more than onevoltage, can be estimated. In either case, the resistance of either orboth multiple strain-sensitive electrodes can be calculated via Ohm'slaw and can, in turn, be correlated to an amount of strain experiencedby one or more of the multiple strain-sensitive electrodes.

In many cases, differential property estimates can be combined with orcompared to common property estimates. In some examples, thedifferential property estimate and common property estimate can becombined by unweighted or weighted averaging. In other embodiments, themaximum or minimum of the two estimates can be used. In still furtherexamples, other methods of combining or deciding between the twoestimates can be used.

In other cases, an actual calculation of resistance for each independentelectrode may not be required. For example, in certain embodiments, anestimated voltage or current (e.g., from a common property estimate,differential property estimate, or both) can be correlated directly toan amount of strain experienced by the force-sensitive structure.

Once the resistance of each electrode is obtained via calculation orestimate, each can be compared to a known baseline resistance value inorder to estimate whether the strain-sensitive electrodes areexperiencing tension or compression. In other words, when theforce-sensitive structure experiences an application of force (e.g., asa result of applying a force to the input surface), it may deform,causing one or more strain-sensitive electrodes to either expand (e.g.,tension) or contract (e.g., compression), which can cause the resistancethereof to change in a mathematically predictable manner.

The foregoing description of the embodiments depicted in FIGS. 4K-4M,and various alternatives and variations, are presented, generally, forpurposes of explanation, and to facilitate a general understanding ofpossible placements of strain-sensitive electrodes relative tocantilevered legs of force-sensitive structures as described withrespect to stylus embodiments disclosed herein. However, it will beapparent to one skilled in the art that some of the specific detailspresented herein may not be required in order to practice a particulardescribed embodiment, or an equivalent thereof.

For example, it is understood that, although these and other embodimentsare described herein with reference to strain-sensitive electrodes, anyforce-sensitive and/or strain-sensitive element can be included forparticular embodiments. Similarly, a cantilevered leg can take anysuitable shape.

Generally and broadly, FIGS. 5A-5N reference different embodiments of arigid signal conduit of a coordination engine of a stylus such asdescribed herein. A user manipulates the stylus to change the relativelocations of a tip field and a ring field. An electronic devicecalculates the relative positions of the fields and, in response,locates and estimates the angular position of the stylus.

For example, FIG. 5A depicts a side view of a portion of a coordinationengine 500 of a stylus. As with the embodiment described with respect toFIG. 3A, the coordination engine 500 includes a tubular shield 502configured to receive a core insert 504 therein. The tubular shield 502has a tray section 506 into (or onto) which a control board 508 can bepositioned. The tubular shield 502 has a hollow portion 510 into whichthe core insert 504 is placed.

The core insert 504 may be configured to convey electrical signalsreceived from the control board 508 to a tip-field generator 512 and aring-field generator 514. In some embodiments, a ground ring 513 can bedisposed between the tip-field generator 512 and the ring-fieldgenerator 514. The ground ring 513 can help prevent capacitive couplingbetween the tip-field generator 512 and the ring-field generator 514.

The core insert 504 may be a shielded signal path; one or more signalpaths within the core insert 504 can be shielded from the other signalpaths in order to prevent capacitive coupling therebetween.

When assembled and operating, the tip-field generator 512 may generateand/or emit the tip field 516, and the ring-field generator 514 maygenerate and/or emit the ring field 518. The tip field 516 and the ringfield 518 can be generated at different powers, such as shown in FIG. 5Bin which the ring field 518 is generated at a higher power than the tipfield 516. In other cases, the tip field 516 and the ring field 518 aregenerated at substantially the same power, such as shown in FIG. 5C.

The tip-field generator 512 may be configured to generate an electricfield (e.g., the ring field) that is approximately spherical in naturewhen estimated from a particular distance. In other words, the tip-fieldgenerator 512 may function, substantially, as an electric field pointsource.

In the illustrated embodiment, the ring-field generator 514 takes theshape of a closed ring through which the tip signal line passes. In thismanner, the ring-field generator 514 may not interfere with the tipsignal, and both the ring field 518 and the tip field 516 may besubstantially spherical and coaxially aligned, such as illustrated inFIG. 5B.

The ring-field generator 514 generates the ring field 518. Thering-field generator 514 can be formed in any number of suitable shapessuch as, but not limited to: a cylindrical shape (e.g., such as shown),a crown shape, a series of rings, a distribution of lines (e.g.,Fibonacci sequence of lines and/or rings), and so on.

Despite the annular shape of the ring-field generator 514, the ringfield 518 is substantially spherical in many embodiments. Morespecifically, as may be appreciated by a person of skill in the art, anelectric field generated by a ring-shaped element can be modeled by theequation:

$\begin{matrix}{E = \frac{k \cdot Q \cdot a}{\left( {r^{2} + a^{2}} \right)^{\frac{3}{2}}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

The equation above describes the magnitude of the electric field E, whenestimated from a distance a from the geometric center of the ring-shapedelement having a radius r to which a charge Q is applied. As may beknown, Coulomb's constant k provides a scaling factor and unitcorrection in order to accurately estimate the electric field E.

When the distance a from the geometric center of the ring-shaped fieldgenerator is much larger than the radius r, the electric field E isapproximately equal to:

$\begin{matrix}{{E \cong \frac{k \cdot Q}{a^{2}}},{a\operatorname{>>}r}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

Therefore, for embodiments in which the distance between the ring-fieldgenerator 514 and an input surface of an electronic device is greaterthan the radius of the ring-field generator 514, the ring field 518 mayappear to be substantially spherical to an input surface, despite thatthe ring-field generator 514 is not, at least geometrically, a pointsource.

In other words, for many embodiments, the radius of the ring-fieldgenerator 514 is selected to be smaller than the distance from thering-field generator 514 to the input surface. In this manner, the ringfield 518 appears to an input surface as a substantially sphericalelectric field generated by a point charge. In this manner, both the tipfield 516 and the ring field 518 are substantially spherical, at leastin the direction of the tip of the stylus.

However, although many embodiments are described herein with referenceto coaxially aligned spherical fields generated by a stylus that aredetected by generally circular groupings of sensors within an electronicdevice, such a configuration may not be required of all embodiments. Insome examples, the ring field generated by a ring-field generator cantake a non-spherical shape. For example, a ring-field generator can beconfigured to generate a substantially conical shape. In this example,the ring field intersection area may be a conic section (e.g.,hyperbola, ellipse, circle, and so on). In other examples, a ring-fieldgenerator can be configured to generate more than one electric field.For example, a ring-field generator can be configured to generate foursubstantially conical electric fields, each evenly spaced from oneanother. The conical electric fields may alternate in polarity or may beassociated with different ring signals so that adjacent conical electricfields do not interfere with one another. In this example, the ringfield intersection area may be a series of conic sections (e.g.,hyperbola, ellipse, circle, and so on). It is therefore appreciated thatany suitable electric field shape, or series of electric field shapes,can be generated by a ring-field generator of a particular embodiment.

FIG. 5D depicts a cross-section of the core insert 504 of thecoordination engine 500, taken through section line C-C of FIG. 5B. Asnoted above, the core insert 504 includes a signal line dedicated toconveying the tip signal to the tip-field generator 512 (the tip signalline) and another signal line dedicated to conveying the ring signal tothe ring-field generator 514 (the ring signal line). In addition, one ormore grounding layers, sheaths, or other structures can enclose the ringsignal line within the ring-field generator 514. Thus, generally andbroadly, the core insert 504 includes several sets of conductors thatare configured to transmit one or more electrical signals therethrough.

The tip-field generator 512 can be formed from any number of suitableelectrically conductive materials. In some examples, the tip-fieldgenerator 512 is formed from metal or a metallized material. In othercases, the tip-field generator 512 is formed from an electricallyconductive polymer or fiber such as an electrically-conductive siliconeor an electrically-conductive nylon. In some cases, the tip-fieldgenerator 512 is formed from a single material, whereas in otherembodiments the tip-field generator 512 is formed from more than onematerial. In some cases, the tip-field generator 512 is rigid, whereasin other cases, the tip-field generator 512 may be at least partiallycompliant and/or flexible. In one example, the tip-field generator 512may be implemented as a pogo pin that is at least partially collapsible.The pogo pin can include a spring and two or more interlocking slidablemembers. Example embodiments of the tip-field generator 512 aredescribed with reference to FIGS. 6A-6G.

The tip-field generator 512 may be formed into the shape of an invertedbulb. A rounded end of the bulb is oriented toward the tip end of thestylus. The rounded end can take a substantially spherical shape or, inother embodiments, a substantially hemispherical shape. A root end ofthe bulb is oriented to extend into the interior of the stylus. Therounded end of the bulb may be configured to act as an electric fieldpoint source. In other words, the rounded end of the bulb may be formedinto a shape that may generate a substantially spherical electric fieldtherefrom. In many cases, the root end of the bulb of the tip-fieldgenerator 512 decreases in diameter away from the rounded end of thebulb shape. The decrease in diameter can be constant, stepped, or mayfollow a mathematical function such as an exponential decay function.

The ring-field generator 514 can be formed from any number of suitableelectrically conductive materials. In some examples, the ring-fieldgenerator 514 is formed from metal. In other cases, the ring-fieldgenerator 514 is formed from a deposited electrically conductivematerial, such as a metal-oxide or a metal powder.

The ring-field generator 514 can be formed in any suitable manner. Inmany cases, many examples (and as illustrated), the ring-field generator514 is disposed on an exterior surface of the core insert 504. Thering-field generator 514 can be disposed onto the external surface ofthe core insert 504 using any number of suitable manufacturingtechniques, including, but notlimited to: physical vapor deposition,pulsed laser deposition, self-adhering conductive film, metallic leafingtechniques, metallic plating techniques, and so on. In some embodiments,the ring-field generator 514 is formed using a laser direct structuringtechnique and formed directly on the outer surface of the core insert504.

The ring-field generator 514 may be coupled to the ring signal line inany electrically suitable manner. In one example, a via 520 through thecore insert 504 connects the ring signal line to the ring-fieldgenerator 514, which can terminate in a standoff electrode 522. In manycases, the via 520 takes a notched (e.g., inverted conical) shape. Thevia 520 connects the standoff electrode 522 to the ring-field generator514. An electrical connection 520 a traversing the via 520 can bedisposed onto the external surface of the core insert 504 or an internalsidewall of the via 520 using any number of suitable manufacturingtechniques, including, but notlimited to: physical vapor deposition,pulsed laser deposition, laser direct structuring, self-adheringconductive film, metallic leafing techniques, metallic platingtechniques, and so on. In some cases, the via 520 can be completelyfilled with a metal material, although this may not be required.

As noted with the embodiment depicted in FIG. 3A, the tip signal lineterminates in a contact pad 524 at an end of the core insert 504. Inthese embodiments, the contact pad 524 can couple to the tip-fieldgenerator 512 in any electrically-suitable manner.

As noted with respect to other embodiments described herein (and asillustrated), the tip-field generator 512 and the ring-field generator514 are co-axially aligned along the length of the core insert 504 sothat the tip field 516 and the ring field 518 are axially aligned andare axially symmetric. As may be appreciated, the spherical nature ofthe tip field 516 and the ring field 518, of many embodiments,facilitate the operations of locating the stylus on an input surfaceand, additionally, estimating the angular position of thereof.

The core insert 504 can be constructed in a number of ways. For example,with particular reference to FIG. 5E which shows a cross-section of thecore insert 504 when taken through line D-D, the core insert 504 caninclude a multi-layer circuit board 526 that is disposed within adielectric bulk 528. For simplicity of illustration, the layers of themulti-layer circuit board 526 are omitted from FIGS. 5D-5E, but it maybe appreciated that the multi-layer circuit board 526 can have anysuitable number of layers, oriented in any suitable manner. In oneexample, the multi-layer circuit board 526 has eight layers.

The dielectric bulk 528 is typically formed from plastic or anothersuitable electrically insulating material. For increased rigidity, thedielectric bulk 528 can be doped with a fiber material, such as glass.

In many examples, the via 520 can be defined during the molding of thedielectric bulk 528 and the multi-layer circuit board 526. For example,the multi-layer circuit board 526 may be held within a mold by a supportthat, when removed after molding, defines the via 520.

The multi-layer circuit board 526 can include any number of suitablecomponents disposed at any particular and suitable location along thelength of the multi-layer circuit board 526. For example, themulti-layer circuit board 526 can include (and/or can be coupled to) oneor more electrical circuit components (not shown) such as, but notlimited to: processors, resistors, capacitors, inductors, transistors,signal lines, ground lines, ground connections, and the like. In manyembodiments, the components that are coupled to the multi-layer circuitboard 526 are laid out and distributed in a manner that reduces and/oreliminates parasitic capacitance. Particularly, the layout of thecomponents of the multi-layer circuit board 526 may be selected so as toreduce or eliminate cross-talk (e.g., parasitic mutual capacitance)between a tip signal line 530 and a ring signal line 532. This may beparticularly desirable to prevent the ring signal from being detected bythe electronic device as a result of the tip field and, similarly, toprevent the tip signal from being detected by the electronic device as aresult of the ring field.

For example, as illustrated, the tip signal line 530 is separated andisolated from the ring signal line 532 by several ground signal lines534. In this embodiment, six independent ground signal lines separate,both physically and electrically, two tip signal lines (each identifiedas the tip signal line 530) and two ring signal lines (each identifiedas the ring signal line 532). In this manner, the several ground signallines 534 provide electrical isolation between the ring signal line(s)and the tip signal line(s).

In many cases, the external surface area of the various signal linespassing through the multi-layer circuit board 526 can also be selectedso as to reduce the possibility of the development of parasiticcapacitance. Particularly, the ground signal line(s), tip signalline(s), and ring signal line(s) can all be relatively thin; the greaterthe outer surface area of any of the signal lines, the greater thechange that parasitic capacitance may develop. In many embodiments, suchas the illustrated embodiment, each signal can be conveyed over morethan one signal line (e.g., two signal lines convey the ring signal, twosignal lines convey the tip signal, six signal lines are grounded) sothat the signals are received at the tip-field generator 512 and thering-field generator 514 without substantial resistive losses resultingfrom the thinness of a single signal line.

As may be appreciated, although the illustrated embodiment depicts sixground lines separating two ring signal lines and two tip signal lines,such quantities are not required of all embodiments. In some cases, moresignal lines or fewer signal lines can be included. In some cases,signal lines that convey the same signal can be connected together atvarious points along the length of the multi-layer circuit board 526 byone or more vias (not shown).

As noted above, a contact pad 524 is disposed at an end of the coreinsert 504. In many cases, the contact pad 524 is soldered to the end ofthe core insert 504. In other cases, the contact pad 524 is formed ontothe end of the core insert 504 by a suitable process, such as, but notlimited to: physical vapor deposition, pulsed laser deposition,laser-direct structuring, self-adhering conductive film, metallicleafing techniques, metallic plating techniques, and so on.

The multi-layer circuit board 526 of the core insert 504 can terminatewith an in-fill section (not labeled) in which a number of viaselectrically couple several layers of the multi-layer circuit board 526to the same electrical circuit or signal line. In many embodiments, eachof the vias and signal lines are electrically coupled to the tip signalline 530. For example, FIG. 5F depicts a cross-section of the coreinsert 504 taken through line E-E of FIG. 5D, along the in-fill section.For clarity, the contact pad 524 is not shown in FIG. 5F.

During manufacturing, the multi-layer circuit board 526 can be cutthrough the in-fill section, thereby causing one or more vias 536 andone or more signal lines 538 a, 538 b to be exposed. The one or moresignal lines 538 a, 538 b can be parallel or perpendicular to the lengthof the multi-layer circuit board 526. In other examples, the signallines can be oriented in another manner, such as along an angle. In thismanner, the exposed vias and signal lines (which are coupled to the tipsignal line 530) exhibit a large total electrically-conductive surfacearea when cut. This large area can couple to (or serve as a portion of)the contact pad 524 using any suitable method. The increased surfacearea provides for a more mechanically and electrically sound couplingbetween the tip signal line 530 and the contact pad 524.

In some embodiments, the contact pad 524 may not be required; theexposed areas of the in-fill region can serve to convey the tip signalto the tip-field generator 512. In other cases, the contact pad 524 canbe a deposit of electrically conductive material that is disposed ontothe exposed areas of the in-fill region.

The length of the in-fill region of the core insert 504 can vary fromembodiment to embodiment and may depend upon manufacturing tolerancethat may be achieved when manufacturing the core insert 504. Forexample, the in-fill region can be long (e.g., extend for a certaindistance inwardly through the length of the multi-layer circuit board526) if a particular implementation is manufactured with low tolerances.In other cases, the in-fill region can be short if a particularimplementation is manufactured with high tolerance. It may beappreciated, similarly, that the number and density of vias can varyfrom embodiment to embodiment, Similarly, the number and density ofsignal lines (however oriented) can also vary from embodiment toembodiment.

Next, reference is made to FIGS. 5G-5I, in which a side view of a stylusgenerating a tip field 516 and a ring field 518 (of differentmagnitudes) that each intersect an input surface 540 of an electronicdevice is shown. Particularly, these figures illustrate (additionallyand supplemented by a removed top view), the relative position of a tipfield intersection area 542 and a ring field intersection area 544 whenthe stylus tilts across the input surface.

FIG. 5G depicts the relative position of the tip field intersection area542 and the ring field intersection area 544 when the stylus is orientednormal to the input surface 540. Particularly, the tip fieldintersection area 542 and the ring field intersection area 544 arecoaxially aligned.

FIG. 5H depicts the relative position of the tip field intersection area542 and the ring field intersection area 544 when the stylus is orientedat an acute polar angle (e.g., tilting to the left) to the input surface540. Particularly, the tip field intersection area 542 remains insubstantially the same position as depicted in FIG. 5G; however, thering field intersection area 544 shifts to the left.

FIG. 5I depicts the relative position of the tip field intersection area542 and the ring field intersection area 544 when the stylus is orientedat an acute polar angle (e.g., tilting to the right) to the inputsurface 540. Particularly, the tip field intersection area 542 remainsin substantially the same position as depicted in FIG. 5G, however, thering field intersection area 544 shifts to the right.

The operation of locating the stylus based on the location of the tipfield intersection area and the ring field intersection area can becompleted as follows, although it is appreciated that the embodimentpresented below is merely one of many methods and techniques that may beemployed in the course of locating a stylus by an electronic device.Similarly, it is appreciated that the equations and techniques presentedbelow are merely examples, and many methods and equations related orunrelated to those presented below may be employed in the course oflocating a stylus such as described herein.

FIG. 5J depicts the stylus of FIG. 5G, particularly illustrating theazimuthal angle φ and polar angle θ of the angular position of thestylus relative to the plane of the input surface of the electronicdevice.

In these embodiments, generally and broadly, the electronic device scansa number of sensors associated with the input surface 540 for the tipsignal. Upon estimating that a group of adjacent sensors all detect thepresence of the tip signal, the electronic device can estimate thegeometric center of said group. As noted above, the group of adjacentsensors typically takes the shape of a circle. The electronic devicethereafter records the coordinates of the geometric center of the grouprelative to an origin point of the input surface 540 as a proxy for thelocation of the tip-field generator, and, more generally, the point atwhich the tip portion of the stylus touches the input surface 540. Forexample, the geometric center (x_(c), y_(c)) of a circle having a radiusr in the Cartesian coordinate system can be estimated by substituting atleast two estimated points (x_(m1), y_(m1)) and (x_(m2), y_(m2)) thatfall on the circumference of the circle into a system of equations:

$\begin{matrix}\left\{ \begin{matrix}{r^{2} = {\left( {x_{m\; 1} - x_{c}} \right)^{2} + \left( {y_{m\; 1} - y_{c}} \right)^{2}}} \\{r^{2} = {\left( {x_{m\; 2} - x_{c}} \right)^{2} + \left( {y_{m\; 2} - y_{c}} \right)^{2}}}\end{matrix} \right. & {{Equation}\mspace{14mu} 3}\end{matrix}$

The system of equations presented above are solvable; the only twounknown variables are the coordinates of the geometric center (x_(c),y_(c)). In this manner, the electronic device can determine the locationof the stylus on the input surface 540 by calculating the geometriccenter 546 of the tip field intersection area 542.

The operation of determining the angular position (e.g., the azimuthalangle φ and the polar angle θ) of the stylus based on the location ofthe tip field intersection area 542 and the ring field intersection area544 can be completed as follows, although it is appreciated that theembodiment presented below is merely one of many methods and techniquesthat may be employed in the course of determining the angular positionof a stylus by an electronic device.

For example, if the Cartesian coordinates of the geometric center 546 ofthe tip field intersection area 542 are (x_(t), y_(t)) and the Cartesiancoordinates of the geometric center 548 of the ring field intersectionarea 544 are (x_(r), y_(r)), and the distance separating the tip-fieldgenerator 512 and the ring-field generator 514 is d, then one method ofestimating the polar angle θ of the stylus can be modeled orapproximated by:

$\begin{matrix}{\theta \cong {\cos^{- 1}\left( \frac{\sqrt{\left( {x_{t} - x_{r}} \right)^{2} + \left( {y_{t} - y_{r}} \right)^{2}}}{d} \right)}} & {{Equation}\mspace{14mu} 4}\end{matrix}$

In this case, when the distance between the centers of the tip fieldintersection area 542 and the ring field intersection area 544 areapproximately equal to the distance separating the tip-field generatorand the ring-field generator (e.g., the stylus is as flat as possible onthe input surface), the inverse cosine operation results in a polarangle θ that approaches 0 radians.

Alternatively, when the distance between the centers of the tip fieldintersection area 542 and the ring field intersection area 544 areapproximately equal to zero (e.g., the stylus is normal to the inputsurface), the inverse cosine operation results in a polar angle θ thatapproaches

$\frac{\pi}{2}$

radians, or ninety degrees.

Similarly, an azimuthal angle φ of the stylus can be calculated. As maybe appreciated, an azimuthal angle φ can be estimated with reference toany suitable vector quantity, such as a reference vector {right arrowover (v_(x))}, that is parallel to a horizontal axis (e.g., the x axis)of a Cartesian coordinate system. It may be appreciated that anysuitable reference vector that is parallel to the plane of the inputsurface 540 can be chosen. For example, in some cases, a referencevector {right arrow over (v_(y))} may be used that is parallel to avertical axis (e.g., the y axis) of a Cartesian coordinate system. Inanother example, an arbitrarily angled reference vector can be used.

A stylus vector, {right arrow over (v_(m))}, defined through the centerof the tip field intersection area 542 (x_(t), y_(t)) and the center ofthe ring field intersection area 544 (x_(r), y_(r)), can be input to thecosine formula for dot product in order to estimate the angle betweenstylus vector and the axis vector. For example, the operation can beperformed by the following equation:

$\begin{matrix}{\varphi = {\cos^{- 1}\left( \frac{\overset{\rightarrow}{v_{x}} \cdot \overset{\rightarrow}{v_{m}}}{{\overset{\rightarrow}{v_{x}}} \cdot {\overset{\rightarrow}{v_{m}}}} \right)}} & {{Equation}\mspace{14mu} 5}\end{matrix}$

In this case, when the horizontal distance between the geometric centers546, 548 of the tip field intersection area 542 and the ring fieldintersection area 544 are approximately equal to zero (e.g., the stylus,regardless of the polar angle θ, is substantially parallel to a verticalaxis of the input surface), the inverse cosine operation results in anazimuthal angle φ that approaches

$\frac{\pi}{2}$

moans, or ninety degrees.

Alternatively, when the vertical distance between the centers of the tipfield intersection area 542 and the ring field intersection area 544 areapproximately equal to zero (e.g., the stylus, regardless of the polarangle θ, is substantially parallel to a horizontal axis of the inputsurface), the inverse cosine operation results in an azimuthal angle φthat approaches 0 radians, or 0 degrees.

In still further embodiments, tip fields and ring fields can begenerated in another manner. For example, FIGS. 5K-5M depict a side viewof a stylus generating a tip field 516 and a ring field 518 (of the samemagnitudes) that each intersect an input surface 540 of an electronicdevice. Particularly, these figures illustrate (additionally andsupplemented by a removed top view), the relative position of a tipfield intersection area 542 and a ring field intersection area 544 whenthe stylus tilts across the input surface.

FIG. 5K depicts the relative position of the tip field intersection area542 and the ring field intersection area 544 when the stylus is orientednormal to the input surface 540. Particularly, the tip fieldintersection area 542 and the ring field intersection area 544 arecoaxially aligned. In this example, the ring field intersection area 544may not be detectable.

FIG. 5L depicts the relative position of the tip field intersection area542 and the ring field intersection area 544 when the stylus is orientedat an acute polar angle (e.g., tilting to the left) to the input surface540. Particularly, the tip field intersection area 542 remains insubstantially the same position as depicted in FIG. 5K, however, thering field intersection area 544 shifts to the left.

FIG. 5M depicts the relative position of the tip field intersection area542 and the ring field intersection area 544 when the stylus is orientedat an acute polar angle (e.g., tilting to the right) to the inputsurface 540. Particularly, the tip field intersection area 542 remainsin substantially the same position as depicted in FIG. 5K, however, thering field intersection area 544 shifts to the right. In furtherexamples, the ring field intersection area 544 can increase in size asthe polar angle of the stylus decreases, such as shown in FIG. 5N.

Generally and broadly, FIGS. 6A-6E reference different embodiments of anosepiece and tip-field generator of a stylus such as described herein.The nosepiece can be removable, interchangeable, or permanently affixedto the stylus. As with other embodiments described herein, a user slidesthe nosepiece across the input surface of an electronic device, therebychanging the location of the tip field generated by the tip-fieldgenerator disposed within the nosepiece. It may generally beadvantageous that the nosepiece provide a durable and non-damagingcontact with the input surface while also securing the tip-fieldgenerator in an accurate and repeatable position with respect to theinput surface.

FIG. 6A depicts a cross-sectional view of a nosepiece 600 a of a stylus,specifically depicting one example of a tip-field generator 602. Thetip-field generator 602 is implemented as a bulb-shaped pogo pin formedfrom a conductive material. The bulb of the tip-field generator 602includes a rounded portion 604 and a root portion 606.

The rounded portion 604 of the bulb of the tip-field generator 602 isformed to take a substantially hemispherical shape. Thus, the electricfield generated thereby (and oriented, generally, in the direction therounded portion 604 faces) is substantially spherical.

The root portion 606 of the bulb of the tip-field generator 602 isformed to taper away from the rounded portion 604. In the illustratedembodiment, the root portion 606 tapers by following a stair-steppattern, although this may not be required of all embodiments. Forexample, the root portion 606 of the bulb can taper linearly or byfollowing an exponential decay function.

At the end of the root portion 606 that is opposite the rounded portion604 of the bulb, the root portion 606 includes a retaining lip 608. Theretaining lip 608 may be configured to retain a pin 610 of the tip-fieldgenerator 602 within a cavity defined in the tip-field generator 602. Abiasing spring 612 may be configured to bias the pin 610 in a directionopposite the rounded portion 604 of the bulb. The pin 610 is configuredto maintain electrical contact with one or more conductive traces formedinto the end of the rigid signal conduit 620. In some embodiments, aconductive paste or conductive medium is placed between the pin 610 andthe rigid signal conduit 620 to facilitate an electrical conduction andminimize parasitic capacitance at the interface between the twocomponents.

In some examples, the rigid signal conduit 620 can be serrated,textured, patterned, or otherwise non-planar at the end which interfacesthe tip-field generator. These features of the rigid signal conduit 620can increase the friction between the two elements, thereby preventingaccidental electrical disconnections therefrom. In other cases, theserrations of the rigid signal conduit 620 can increase the surface areawith which the pin 610 may contact the rigid signal conduit 620.

The rounded portion 604 of the tip-field generator 602 may be formedfrom a metal or other conductive material that is configured to producethe desired tip field. However, in some embodiments, the material of therounded portion 604 may be too hard to slide across the input surface ofthe device without scratching or risking damage to the surface. Thus,the nosepiece 600 a may include one or more layers of material that areconfigured to provide reliable, non-marking contact with the inputsurface and also maintain structural and dimensional integrity of thenosepiece 600 a.

The nosepiece 600 a may be formed from one or more layers of materialthat, in some embodiments, may have a hardness that is less than thematerial of the tip-field generator 602. The different layers ofmaterial confer different electrical or mechanical properties to thenosepiece 600 a. In other cases, the nosepiece 600 a is formed from asingle material, such as depicted in FIG. 6B.

Returning to FIG. 6A, the nosepiece 600 a can include a structural layer614. The structural layer 614 is typically formed from a rigid,structurally enhanced material, such as glass-doped plastic, acrylic,fiber-reinforced plastic or polymer, metal, and the like. In someembodiments, the structural layer 614 is formed from a polyamidematerial including, for example, nylon, Zytel, Kevlar, Rilsan, or thelike. The structural layer 614 can be formed with a threaded portion616. The threaded portion 616 is configured to couple the nosepiece 600a to an electromechanical coupling and/or a tubular shield such asdescribed herein. The nosepiece 600 a may be a disposable,substitutable, or replaceable component.

The nosepiece 600 a also includes an exterior layer 618. The exteriorlayer 618 is typically formed from a non-conductive material, such asplastic or nylon. While in some embodiments, the exterior layer 618 canbe doped with a fiber material, such as glass for structural rigidity,in other embodiments, the exterior layer 618 is substantially free offiber or other reinforcing material. An exterior layer 618 that issubstantially free of fiber or other reinforcing material may beparticularly suitable for contact with softer input surfaces or inputsurfaces with a delicate coating or surface treatment. In some cases,the hardness of the exterior layer 618 is selected to be lower than thehardness of an input surface of an electronic device. In someembodiments, the exterior layer 618 is formed from a softer polymerincluding, for example, low durometer nylon or other polyamide,polyether (e.g, Pebax), elastomer, and the like. The exterior layer 618can be formed over the structural layer 614, with the structural layer614, or entirely separately from the structural layer 614.

Generally and broadly, it is understood that the tip-field generator602, the exterior layer 618, and the structural layer 614 can bemanufactured together or separately using any suitable manufacturingprocess, such as, but not limited to: a two-shot molding process, aco-molding process, an overmolding process, an insert molding process,or any other suitable process. Such manufacturing processes may enablethe exterior layer 618 and the structural layer 614 to be mechanicallycoupled using one or more undercut or interlocking features and may alsoreduce gaps or voids formed between the two layers. In some embodiments,one or both of the layers are overmolded directly onto the tip-fieldgenerator 602 using an insert-molding manufacturing process. In somecases, the exterior layer 618 can be painted or inked with a cosmetic(or functional) layer of pigmented material.

In this manner, once assembled onto a stylus, the pin 610 of thetip-field generator 602 makes electrical contact to a rigid signalconduit 620 within the stylus. In other embodiments, a nosepiece of astylus can be implemented in different ways. For example, FIG. 6Cdepicts a cross-section of a nosepiece of a stylus that includes both atip-field generator and a ring-field generator.

The nosepiece 600 b of the stylus is formed to take the shape of anaxial electrical connection, such as that of a headphone connector orplug (e.g., tip-ring-sleeve or tip-ring-ring-sleeve connectors). Thenosepiece 600 b may be a disposable, substitutable, or replaceablecomponent. The nosepiece 600 b includes a tip-field generator 622 and aring-field generator 624. In this embodiment, the nosepiece 600 b takesa generally cylindrical shape, although this may not be required of allembodiments.

The tip-field generator 622 is implemented as a bulb-shaped insert. Thetip-field generator 622 includes a rounded end 626 and a root end 628.

As with the pogo pin embodiment depicted in FIG. 6A, the rounded end 626of the tip-field generator 622 is formed to take a substantiallyhemispherical shape. Thus, the electric field generated thereby (andoriented, generally in the direction the rounded end 626 faces) issubstantially spherical.

The root end 628 of the tip-field generator 622 is formed to taper awayfrom the rounded end 626. In the illustrated embodiment, the root end628 tapers by following a stepped exponential decay pattern, althoughthis may not be required of all embodiments.

At the tip of the root end 628 that is opposite the rounded end 626 ofthe tip-field generator 622, the root end 628 contacts a tip signal line630. The tip signal line 630 is electrically connected to a ring signalcontact 636 exposed at one end of the nosepiece 600 b.

The nosepiece 600 b also includes a ring-field generator 624. In theillustrated embodiment, the ring-field generator 624 is formed into agenerally conical shape although this may not be required of allembodiments. The ring-field generator 624 is electrically coupled to aring signal line 634 that itself may be coupled to a ring signal contact636 exposed as a ring circumscribing the nosepiece 600 b.

A first ground signal line 638 is disposed around both the tip signalline 630 and the ring signal line 634. A second ground signal line 640is disposed between the tip signal line 630 and the ring signal line634. In this manner, the first ground signal line 638 and the secondground signal line 640 provide electromagnetic shielding to both the tipsignal line 630 and to the ring signal line 634. The first ground signalline 638 and the second ground signal line 640 terminate, respectively,in the first ground signal contact 642 and the second ground signalcontact 644, each exposed as a ring circumscribing the nosepiece 600 b.

To facilitate a clear understanding of this embodiment, FIGS. 6D-6E areprovided. FIG. 6D shows the nosepiece 600 b without the first groundsignal line 638 and the second ground signal line 640, more clearlyshowing the tip signal line 630 and the ring signal line 634. The bodyof the nosepiece 600 b is presented in phantom. Similarly, FIG. 6E showsthe nosepiece 600 b without the tip signal line 630 and the ring signalline 634, more clearly showing the first ground signal line 638 and thesecond ground signal line 640. The body of the nosepiece 600 b ispresented in phantom.

As may be appreciated, the tip signal line 630, the ring signal line634, the first ground signal line 638 and the second ground signal line640, the tip signal contact 632, the ring signal contact 636, the firstground signal contact 642, and the second ground signal contact 644 areall formed from electrically conductive materials. The body of thenosepiece 600 b is formed from an electrically insulating material.

In one embodiment, the tip-field generator 622 is molded within a nib646 of the nosepiece 600 b. The nib 646 is formed from anelectrically-conductive plastic or polymer material. The hardness of thenib 646 may be selected to be lower than the hardness of an inputsurface of an electronic device. For increased rigidity, the nib 646 canbe doped with a fiber material, such as glass.

The nib 646 can be formed from a material that is different from thematerial used to form a body of the nosepiece 600 b, which can be formedfrom a rigid material, such as glass-doped plastic, acrylic, metal, andthe like.

In many cases, the taper of the root end 628 is selected so that aneffective bond between the nib 646 and the tip-field generator 622 isformed.

Generally and broadly, it is understood that the tip-field generator 622and any other components depicted in the embodiments shown in FIGS.6C-6E can be manufactured together or separately using any suitablemanufacturing process, such as, but not limited to: a two-shot moldingprocess, a co-molding process, an overmolding process, an insert moldingprocess, or any other suitable process.

Other embodiments can take other configurations. FIG. 6F depicts across-section of a nosepiece 600 c of a stylus, specifically depictingone example of a tip-field generator 648. The tip-field generator 648 isimplemented as a bulb-shaped insert. As with other embodiments describedherein, the bulb of the tip-field generator 648 includes a roundedportion 650 and a root portion 652.

The rounded portion 650 of the bulb of the tip-field generator 648 isformed to take a substantially hemispherical shape. Thus, the electricfield generated thereby (and oriented, generally in the direction therounded portion 650 faces) is substantially spherical.

The root portion 652 of the bulb of the tip-field generator 648 isformed to taper away from the rounded portion 650. In the illustratedembodiment, the root portion 652 tapers by following a stair-steppattern, although this may not be required of all embodiments. Forexample, the root portion 652 of the bulb can taper linearly or byfollowing an exponential decay function. In many cases, the taper of theroot portion 652 is selected so that an effective bond between thetip-field generator 648 and another element (e.g., structural layers andso on) is formed.

As with other embodiments described herein, the nosepiece 600 c isformed from one or more layers of material. The different layers ofmaterial confer different electrical or mechanical properties to thenosepiece 600 c. For example, the nosepiece 600 c can include astructural layer 654. The structural layer 654 may be formed from arigid material, such as glass-doped plastic, acrylic, metal, and thelike. The structural layer 654 can be formed with a threaded portion656. The threaded portion 656 may be configured to couple the nosepiece600 c to a coordination engine and/or a tubular shield such as describedherein. In many cases, the taper of the root portion 652 is selected sothat an effective bond between the structural layer 654 and thetip-field generator 648 is formed.

The nosepiece 600 c also includes an ink layer 658. The ink layer 658may be formed from a non-conductive paint. The hardness of the dried inklayer may be selected to be lower than the hardness of an input surfaceof an electronic device.

Generally and broadly, it is understood that the tip-field generator648, the ink layer 658 and the structural layer 654 can be manufacturedtogether or separately using any suitable manufacturing process, suchas, but not limited to: a two-shot molding process, a co-moldingprocess, an overmolding process, an insert molding process, or any othersuitable process.

In this manner, once assembled onto a stylus, the root portion 652 ofthe tip-field generator 648 makes electrical contact to a rigid signalconduit 660 within the stylus. The nosepiece 600 c may be a disposable,substitutable, or replaceable component.

The tip-field generator 648 can be made from any suitable electricallyconductive material. For example, the tip-field generator 648 can be aconductive, polymer such as, but not limited to: conductive silicone,conductive nylon, polyaniline, polythiophene, polypyrrole,polyethylenedioxythiophene, and so on.

In still further embodiments, the tip-field generator 648 can beimplemented in a different manner. For example, as shown in FIG. 6G, thetip-field generator 662 is formed by depositing an electricallyconductive pogo pin 664 at least partially within an electricallyconductive material 666. The electrically conductive material 666 can bean electrically conductive polymer or plastic. For increased rigidity,the electrically conductive material 666 can be doped with a fibermaterial, such as glass.

As with other embodiments described herein, the nosepiece 600 d isformed from one or more layers of material. The different layers ofmaterial confer different electrical or mechanical properties to thenosepiece 600 d. For example, the nosepiece 600 d can include astructural layer 668. The structural layer 668 may be formed from arigid material, such as glass-doped plastic, acrylic, metal, and thelike. The structural layer 668 can be formed with a threaded portionconfigured to couple the nosepiece 600 d to a coordination engine and/ora tubular shield such as described herein. The nosepiece 600 d may be adisposable, substitutable, or replaceable component. An ink layer 670can be coated on the exterior of the electrically conductive material666 and/or the structural layer 668 of the nosepiece 600 d.

In some examples, the electrically conductive pogo pin 664 is supportedwithin the nosepiece 600 d by a support collar 672. The support collar672 can be formed from any number of suitable materials such as, but notlimited to: polymer materials, elastomeric materials, metals, acrylics,ceramics, fiber-reinforced materials, and so on. For increased rigidity,the support collar 672 can be doped with a fiber material, such asglass. The support collar 672 can be formed from the same material asthe electrically conductive material 666, although this is not required.For example, in many embodiments, the support collar 672 is formed froma different material. In some examples, the material selected for theelectrically conductive material 666 is softer than the materialselected for the support collar 672.

Generally and broadly, it is understood that the tip-field generator602, the support collar 672, the structural layer 668, the electricallyconductive pogo pin 664, and the an electrically conductive material 666can be manufactured together or separately using any suitablemanufacturing process, such as, but not limited to: a two-shot moldingprocess, a co-molding process, an overmolding process, an insert moldingprocess, or any other suitable process. For example, in theseembodiments, the support collar 672 can be referred to as a first innershot, and the electrically conductive material 666 can be referred to asa second outer shot of a two-shot molding process.

The foregoing description of the embodiments depicted in FIGS. 6A-6G,and various alternatives and variations, are presented, generally, forpurposes of explanation, and to facilitate a general understanding ofpossible nosepieces including tip-field generators and/or ring-fieldgenerators for use with stylus embodiments disclosed herein. However, itwill be apparent to one skilled in the art that some of the specificdetails presented herein may not be required in order to practice aparticular described embodiment, or an equivalent thereof.

More generally, the foregoing description of the embodiments depicted inFIGS. 3A-6G, and various alternatives and variations, are presented,generally, for purposes of explanation, and to facilitate a generalunderstanding of both movable and grounded sections of a tip portion ofa stylus in accordance with embodiments described herein. It isunderstood that these various components (including, but notlimited to,nosepieces, force-sensitive structures, coordination engines, rigidconduits, and so on) may be assembled together in a number ofimplementation-specific ways.

However, to facilitate an understanding of one possible assembly ofthese components, FIG. 7 is presented, depicting a cross-section of astylus, specifically illustrating a coordination engine connecting thetip to a force-sensitive structure of a force engine and providing asignal path for a tip-field generator and a ring-field generator.

The stylus 700 includes a barrel 702 that tapers at one end. A nosepiece704 is separated from the body at the tapered end by a clearance gap706. When a force is received by the nosepiece 704, the nosepiece 704moves toward the barrel 702 thereby reducing the width of the clearancegap 706. The nosepiece 704 is screwed onto a threaded portion of atubular shield 708 so as to abut a load-shifting nut 710. Theload-shifting nut 710 prevents the nosepiece 704 from becomingundesirably disconnected from the tubular shield 708. The load-shiftingnut 710 may also restrict the bending or twisting of the nosepiece 704with respect to the barrel 702. Specifically, with respect to thecross-sectional view of FIG. 7, the load-shifting nut 710 may limitmovement of the nosepiece 704 in the up and down direction resultingfrom a side or non-axial force exerted on the nosepiece 704.

The tubular shield 708 is mechanically coupled to a portion of aforce-sensitive structure 712. The force-sensitive structure 712 ispartially grounded or otherwise fixed with respect to a chassis 714. Thechassis 714 is rigidly coupled to the barrel 702. The force-sensitivestructure 712 includes a cantilevered leg 716 that is welded to aportion of the chassis 714, thereby mechanically grounding or otherwisefixing one end of the cantilevered leg 716 to the chassis 714. Theforce-sensitive structure 712 also includes a lateral bed 718 that iscoupled to the non-grounded or unfixed end of the cantilevered leg 716.In this manner, the lateral bed 718 (and anything coupled to it) cantranslate laterally within the barrel 702. A lateral translation of thelateral bed may, with respect to FIG. 7, refer to movement generally inthe horizontal direction. One or more stiffeners 720 can be coupled tothe lateral bed 718.

The lateral bed 718 is the portion of the force-sensitive structure 712to which the tubular shield 708 may be coupled. Additionally, thetubular shield 708 may extend, at least partially, through thecantilevered leg 716 which defines an opening 722. In this manner, thetubular shield 708 (or anything coupled to it) can translate laterallywith the lateral bed 718.

In this manner, when a force is received by the nosepiece 704, thenosepiece 704 transfers the force received to the tubular shield 708which, in turn transfers the force to the lateral bed 718 of theforce-sensitive structure 712, causing each of these components totranslate laterally, reducing the width of the clearance gap 706.However, the fixed leg of the cantilevered leg 716 may not move inresponse; thus, the cantilevered leg 716 deforms in response to theforce received.

The chassis 714 may be coupled (e.g., welded to) a flanged nut 724. Awasher 726 can be positioned between the flanged nut 724 and the chassis714. In other examples, the washer 726 can be a foam pad. A supportcollar 728 is screwed onto threads of the flanged nut 724 so that thesupport collar 728 abuts an internal lip 730 defined on an internalsurface of the barrel 702. In other words, the support collar 728 mayprovide an unbroken mechanical connection between the internal lip 730and to the chassis 714.

The tubular shield 708 extends through both the support collar 728 andthe flanged nut 724. Additionally, a second load-shifting nut 732 can bepositioned on the tubular shield 708 so that when the nosepiece 704 isin a neutral position (e.g., not receiving a force), the secondload-shifting nut 732 is separated from the flanged nut 724 by a secondclearance gap 734. The second clearance gap 734 may be less than theclearance gap 706.

In this manner, when a force of high magnitude is received by thenosepiece 704, the nosepiece 704 transfers the force received to thetubular shield 708 which in turn transfers the force to the lateral bed718 of the force-sensitive structure 712, causing each of thesecomponents to translate laterally. Once the assembly has translated adistance sufficient to close the second clearance gap 734, the assemblymay be stopped from further translation by the second load-shifting nut732 and the flanged nut 724. In this manner, the peak mechanical loadthat can be experienced by the force-sensitive structure 712 iscontrolled by the relative position of the second load-shifting nut 732and the flanged nut 724.

The tubular shield 708 is hollow. A rigid conduit 736 extends within thetubular shield 708 to deliver a tip signal to a tip-field generator 738and, additionally, a ring signal to a ring-field generator 740.

The foregoing description of the embodiments depicted in FIG. 7 andvarious alternatives and variations, are presented, generally, forpurposes of explanation, and to facilitate a general understanding ofone possible assembly of a stylus such as disclosed herein. However, itwill be apparent to one skilled in the art that some of the specificdetails presented herein may not be required in order to practice aparticular described embodiment, or an equivalent thereof.

Generally and broadly, FIGS. 8A-8C reference different embodiments of aflexible circuit board of a stylus such as described herein. FIG. 8Adepicts a plan view of a controller board set that may be folded inorder to be received in a thin form factor of a stylus.

The controller board set 800 may include a substrate on or through whichone or more electronic components are disposed. These components may besurface mount or through-hole components. The substrate can be a singlelayer circuit board, a multi-layer circuit board, or a flexible circuitboard. In some examples, a flexible circuit board can be used that ismade rigid with one or more stiffeners.

In the illustrated embodiment, the controller board set 800 includessubstrates that are connected by one or more flexible circuits. A firstcontrol board 802 may be coupled to a second control board 804 via oneor more flexible connectors 806. In many cases, the first control board802 and the second control board 804 take substantially the same shape.In this manner, the second control board 804 can be folded underneaththe first control board 802 (as shown in FIG. 8B, when viewed along lineF-F of FIG. 8A). Thereafter, the first control board 802 and the secondcontrol board 804 can be fastened together in a manner that retains aselected distance between the boards.

In one embodiment, the first control board 802 and the second controlboard 804 can be fastened together with a first standoff 808, a secondstandoff 810, and a spacer 812. The first standoff 808 and the secondstandoff 810 may be disposed at a top edge and a bottom edge of thefolded boards, respectively. The spacer 812 may be positioned generallyin the middle of the first control board 802 and the second controlboard 804.

The first standoff 808 and the second standoff 810 can be fastened tothe boards via one or more mechanical fasteners, such as screws. In manyembodiments the first standoff 808 defines a horizontally-oriented hole808 a and a vertically-oriented hole 808 b. Either or both of thehorizontally-oriented hole 808 a and the vertically-oriented hole 808 bcan extend either partly or entirely through the first standoff 808.Either or both of the horizontally-oriented hole 808 a and thevertically-oriented hole 808 b can be threaded.

Similarly, the second standoff 810 defines a horizontally-oriented hole810 a and a vertically-oriented hole 810 b. Either or both of thehorizontally-oriented hole 810 a and the vertically-oriented hole 810 bcan extend either partly or entirely through the second standoff 810.Either or both of the horizontally-oriented hole 810 a and thevertically-oriented hole 810 b can be threaded to accept fasteners suchas the screws 814, 816 as shown in FIG. 8B.

In other cases, the first standoff 808 and the second standoff 810 areadhered to the boards using an adhesive. In some cases, the firststandoff 808 and/or the second standoff 810 can be electricallyconnected to a circuit ground of either or both boards.

In still other cases, the first standoff 808 and the second standoff 810are surface mounted, soldered, hot barred, or otherwise mechanicallyaffixed to the boards, such as shown in FIG. 8C. In some cases, thefirst standoff 808 and/or the second standoff 810 can be electricallyconnected to a circuit ground of either or both boards via an electricalconnection 818.

The foregoing description of the embodiments depicted in FIGS. 8A-8C andvarious alternatives and variations, are presented, generally, forpurposes of explanation, and to facilitate a general understanding ofone folded circuit board set that may be included within the body orbarrel of a stylus such as disclosed herein. However, it will beapparent to one skilled in the art that some of the specific detailspresented herein may not be required in order to practice a particulardescribed embodiment, or an equivalent thereof. For example, althoughthe depicted embodiment shows two circuit boards of approximately equalwidth, it is appreciated that more circuit boards can be folded togetherin the manner described.

Generally and broadly, FIGS. 9A-9D reference different embodiments of apower connector that can be concealed by a blind cap of a stylus such asdescribed herein. In these embodiments, the blind cap attaches to thepower connector via magnetic attraction. FIG. 9A depicts a powerconnector 900 of a stylus and a cap for concealing the power connectorwhen not in use. The power connector 900 includes a plug 902, a collar904, and a body 906.

The plug 902 extends from the barrel of the stylus. A blind cap 908 canbe placed over the plug 902 to provide a cosmetic termination to thebarrel of the stylus, as well as protecting the plug 902 from damage.

The plug 902 can be configured to couple to a power and/or data port ofan electronic device to facilitate recharging of a battery pack withinthe stylus. In other cases, the plug 902 can be used to exchange databetween the stylus and an electronic device (e.g., firmware updates,authentication packets, security certificates, and so on). In manycases, the plug 902 is a male connector configured to mate with a femalereceptacle, but this may not be required in all embodiments. In othercases, the plug 902 may be a female receptacle configured to mate with amale connector. In these embodiments, the blind cap 908 may include amale extension portion configured to fit within the receptacle.

The plug 902 may include at least one element that is ferromagnetic. Inother cases, the plug 902 can include a permanent magnet or aselectably-controllable electromagnet. In this manner, the plug 902 canbe attracted to a ferromagnetic member and/or a permanent magnetdisposed within the blind cap.

The plug 902 can be configured to be flexible (laterally moveable withinthe collar 904) so that when connected to an electronic device, thestylus can resist and withstand certain forces that may otherwise damagethe stylus and/or the electronic device (see e.g., FIGS. 11A-11B). Inmany cases, the plug 902 is flexible in one degree of freedom (e.g., twodirections such as right and left). In other embodiments, the plug 902is flexible in more than one degree of freedom, such as two degrees offreedom (e.g., four directions such as right and left and up and down).

Further, it may be appreciated that although the plug 902 is illustratedas a multi-pin and standardized power connector, such a connector is notrequired. Particularly, in some embodiments, a Lightning connector,Universal Serial Bus connector, Firewire connector, serial connector,Thunderbolt connector, headphone connector, or any other suitableconnector can be used.

In some embodiments, the power connector 900 can retract, eithermanually or automatically, and either partially or entirely, into thebarrel when not in use. In some examples, the power connector 900 can beconnected to a push-push mechanism.

The blind cap 908 can take any suitable shape. As illustrated, the blindcap 908 takes the shape of a capsule half (e.g., a cylinder capped witha hemisphere). The blind cap 908 includes a ring 910 that may beconfigured to sit within a channel defined by the collar 904. The blindcap 908 also includes a pressure vent 912 that may be configured tonormalize the pressure within the blind cap 908 to the pressure of theambient environment. In other words, the pressure vent 912 can beconfigured to prevent and/or mitigate the development of a pressuredifferential that may, in some cases, eject the blind cap 908 from thebarrel of the stylus. In some embodiments, the pressure vent 912 caninclude a valve (not shown) that regulates and/or otherwise controls theairflow therethrough.

In many embodiments, the collar 904 is formed from the same material asthe barrel of the stylus. In other cases, the collar 904 is formed froma different material, such as a metal. In some cases, the collar 904 maybe a heat-treated metal. In many embodiments, the collar 904 has a lowmagnetic permeability, although this is not required. In many cases, thecollar 904 may include a seal (not shown) that connects the collar 904directly to an external surface of the plug 902. The seal can permit theplug 902 to move within the collar and the seal can connect a metalportion of the plug 902 to a non-metal portion of the collar 904. Inother embodiments, the collar 904 can couple to the plug 902 in adifferent manner. In some cases, the collar 904 can be coupled to acircuit ground or can be coupled to a sensor circuit within the stylusso that the stylus may be able to determine whether the blind cap 908 isattached to the barrel of the stylus.

The collar 904 can provide structural support to one or more componentsof the stylus or the power connector 900. For example, the collar 904can at least partially seal the barrel of the stylus. However, in othercases, the collar 904 may not be required to provide structural supportto the stylus or to the power connector 900. For example, in some cases,the collar 904 may be configured such that the attachment of the powerconnector 900 is not solely dependent upon the collar 904 (e.g., acosmetic and/or other non-structural feature). In these cases, if thecollar 904 should fail (e.g., crack, break, detach, and so on), thepower connector 900 may remain attached to the barrel of the stylus andmay remain functional.

In some embodiments, the collar 904 can be engraved or etched to includesymbols, text, or patterns that can serve to identify the manufactureror user of the stylus.

FIG. 9B depicts the power connector 900 and the blind cap 908 of FIG.9A, shown in cross-section through line G-G. The power connector 900 maybe formed, at least partially, from a ferromagnetic material. The collar904 includes a potted junction 914. The potted junction 914 electricallycouples a circuit board extending from the power connector 900 to one ormore leads 916. Additionally, the potted junction 914 is covered,coated, or otherwise potted and/or sealed with a flexible material, suchas silicone, a polymer, or an elastomer. The potted junction 914 permitslimited movement of the power connector 900 without transferring thatmovement to the one or more leads 916.

The one or more leads 916 extend from the potted junction 914 through arelief sleeve 918 that extends from the back portion of the powerconnector 900 to the end of the body 906. The relief sleeve 918 issurrounded by a restoring spring 920.

In this manner, when the power connector 900 is connected to anelectronic device and a torque is applied to the stylus, said torque istransferred into the relief sleeve 918 and the restoring spring 920,permitting the barrel of the stylus (not shown) to at least partiallyflex away from the power connector 900. This arrangement allows thestylus to receive and/or absorb a certain amount of torque when thestylus is connected to an electronic device. This flexibility of thepower connector 900 prevents damage to both the stylus and an associatedelectronic device.

In many embodiments, the blind cap 908 includes a guide 928 that has agenerally curved profile. The curved profile of the guide 928 encouragesthe power connector 900 into alignment with the blind cap 908.

The blind cap 908 also includes one or more magnets. The magnets areidentified in the illustrated embodiment as the magnets 930 a, 930 b.The one or more magnets 930 a, 930 b are attracted to the powerconnector 900, thereby drawing the power connector 900 through the guide928 and securing the blind cap 908 to the power connector 900. Amagnetic shunt 932 is positioned behind the magnets. The magnetic shunt932 is formed from a material with a high magnetic permeability. In thismanner, the magnetic shunt 932 redirects the flux of the magnets 930 a,930 b back toward the plug 902. Similarly, the magnetic shunt 932redirects the flux of the magnets 930 a, 930 b away from the rounded endof the blind cap 908. In some cases, the magnetic shunt 932 is amagnetically permeable sheet (e.g., iron, cobalt-iron, and so on) thatis attached to the rear side of the magnets 930 a, 930 b. In othercases, the magnetic shunt 932 may take a specific shape, such as ahemispherical shape.

In many examples, the magnets 930 a, 930 b can be secured within theblind cap 908 with polarities opposing one another. As a result of thisconfiguration, flux may be concentrated toward the guide 928, therebyexhibiting a stronger magnetic attraction to the plug 902.

In some embodiments, an adhesive 934 attaches a guide ring 936 to theface of the magnets 930 a, 930 b. The guide ring 936 can guide the plug902 toward the magnets 930 a, 930 b. In other embodiments, the guidering 936 may be coupled to the guide 928.

As noted above, the magnets 930 a, 930 b are configured to attract toferromagnetic elements within the plug 902. These elements can bespecifically included within the plug 902, or they can be elementsotherwise required for the structural support and/or functionality ofthe plug 902.

Other embodiments may be implemented in other ways. For example, themagnets 930 a, 930 b may be disposed on an outer surface of the guide928, such as depicted in FIG. 9C. In this embodiment, a third largermagnet, labeled as the magnet 930 c, can cover an open end of the guide928. In other embodiments, the magnets 930 a, 930 b and 930 c may bereplaced by a single large magnet 930 d, such as shown in FIG. 9D.

Furthermore, although many embodiments described above referencemagnetic attraction between a blind cap 908 and a plug 902 extendingfrom a body of a stylus (whether such magnets are within the blind cap,the plug, or both), it may be appreciated that other embodiments cancouple the blind cap to a stylus in a different manner consistent withembodiments described herein. For example, in other embodiments,magnetic attraction can be replaced and/or supplemented by aninterference-fit between the blind cap and the plug. For example, one ormore protrusions extending from an internal sidewall of the blind cap908 can be set within one or more detents 902 a, 902 b defined by theplug. In other cases, the blind cap 908 can connect to the plug 902 by athreaded connection. In another embodiment, the blind cap 908 canconnect to the plug 902 by a snap-fit connection.

Generally and broadly, FIGS. 10A-10H reference different embodiments ofa power connector that can be concealed by a blind cap of a stylus suchas described herein. These embodiments depict a blind cap 1000 that isconfigured to attach to and to conceal a plug 1002 of a stylus. Theblind cap 1000 includes a body 1004 that defines an external surface andan internal volume of the blind cap 1000. In many examples, the body1004 is formed from a polymer material, although this may not berequired.

In some embodiments, the body 1004 can be formed with one or moreprotrusions (not shown) that are configured to interface with featuresof the plug 1002 (e.g., detents). In other cases, the body 1004 caninclude one or more springs configured to interface with features of theplug 1002. Certain example embodiments depicting the body 1004incorporating leaf springs are depicted in FIGS. 10A-10C and certainexample embodiments depicting the body 1004 incorporating hoop springsare depicted in FIGS. 10D-10H. In still further embodiments, otherconfigurations of springs may be used.

FIG. 10A depicts a cross-section of the plug 1002 of a stylus and ablind cap 1000 for concealing the plug 1002, particularly showing aconfiguration of leaf springs, labeled in the figure as the leaf springs1006 a, 1006 b, within the body 1004 of the blind cap 1000. The leafsprings 1006 a, 1006 b extend from an interior surface of the body 1004and are configured to engage with corresponding detents in the plug1002, such as shown in FIG. 10B. The detents 1008 a, 1008 b can take anysuitable shape.

In many embodiments, the leaf springs 1006 a, 1006 b are formed frommetal. The leaf springs 1006 a, 1006 b can be insert-molded into thebody 1004. In other cases, the leaf springs 1006 a, 1006 b can beinserted into the body 1004 during manufacturing of the blind cap 1000.In these examples, the leaf springs 1006 a, 1006 b may be permanentlyaffixed to the interior of the body 1004.

The leaf springs 1006 a, 1006 b are depicted in FIGS. 10A-10B asextending from a ring that extends from the base of the body 1004,although this configuration is not required of all embodiments, forexample, the leaf springs 1006 a, 1006 b can be a separate piece fromthe ring, such as depicted in FIG. 10C. In this embodiment, the leafsprings 1010 a, 1010 b extend downwardly to meet the detents 1008 a,1008 b.

In other cases, other springs and/or spring types can be used to retainthe blind cap 1000 to the plug 1002. For example, FIGS. 10D-10E depict ablind cap 1000 and a cross-section thereof. The body 1004 of the blindcap 1000 includes a circular hoop spring. The circular hoop spring isidentified as the hoop spring 1012. In some embodiments, the hoop spring1012 can be a portion of a cosmetic or functional ring (e.g., the ring1014) that extends outwardly from the base of the body 1004 of the blindcap 1000. In other cases, such as shown in FIG. 10D, the hoop spring1012 can be a separate element from the ring 1014.

As depicted in FIGS. 10D-10E, the hoop spring 1012 includes twoindentations, identified as the indentations 1016 a, 1016 b, that areconfigured to engage with the detents 1008 a, 1008 b, such as shown inFIG. 10F.

As with the leaf springs depicted in FIGS. 10A-10C, the hoop spring 1012can be formed from metal. In some cases, the hoop spring 1012 can beinsert-molded into the body 1004. In other cases, the hoop spring 1012can be inserted into the body 1004 during manufacturing of the blind cap1000. In these examples, the hoop spring 1012 may be permanently affixedto the interior of the body 1004.

The hoop spring 1012 can be a portion of a ring 1014. In other cases,the hoop spring 1012 can be separated from the ring 1014. Further,although the hoop spring 1012 is depicted as a single continuous ring,such a configuration is not required of all embodiments. For example,the hoop spring 1012 can be broken into multiple parts, such as shown inFIG. 10G, labeled as the hoop spring parts 1014 a, 1014 b. In othercases, more than one hoop spring can be used, such as shown in FIG. 10H.In this embodiment, two hoop springs, identified as the hoop springs1018 a, 1018 b, are included.

The foregoing description of the embodiments depicted in FIGS. 10A-10Hand various alternatives and variations, are presented, generally, forpurposes of explanation, and to facilitate a general understanding ofvarious methods of attaching a blind cap to a stylus using aninterference-fit technique. However, it will be apparent to one skilledin the art that some of the specific details presented herein may not berequired in order to practice a particular described embodiment, or anequivalent thereof. For example, although the depicted embodiments showvarious spring configurations without magnetic elements, it may beappreciated that any of the embodiments depicted in FIGS. 10A-10H mayincorporate one or more magnets such as shown in FIGS. 9A-9D in order toimprove the attachment of the blind cap to the stylus body.

Many of the embodiments depicted and described herein generallyreference a blind cap that conceals a power connector (e.g., plug) of astylus when the power connector is not in use. As noted above, the powerconnector of a stylus may be used to recharge a battery within thestylus. Generally and broadly FIGS. 11A-11F depict various exampleembodiments of a power connector of a stylus receiving power from anexternal electronic device.

For example, FIG. 11A depicts an electronic device 1100. The electronicdevice 1100 incorporates a power port that can couple to a powerconnector of a stylus 1102. In some cases, such as noted above withrespect to FIGS. 9A-9D, the power connector of the stylus 1102 may beflexible and may be configured to bend in response to a force F appliedto the stylus 1102 when the stylus 1102 is connected to the electronicdevice 1100. For example, FIG. 11B depicts the stylus 1102 bending inresponse to a force F.

In other cases, the stylus 1102 can charge in another manner. Forexample, the stylus 1102 can couple to a dock 1104, such as shown inFIG. 11C. The dock 1104 can be coupled via a data or power cable 1106 toanother electronic device or to an electrical outlet. In other examples,the stylus 1102 couples directly to the data or power cable 1106 via anadapter 1108, such as shown in FIG. 11D.

In still further embodiments, the stylus 1102 may not include a powerconnector such as described in other embodiments. In particular, thestylus 1102 may receive data and/or power from an electronic device viacontacts disposed in the barrel of the stylus 1102, such as shown inFIGS. 11E-11F. In this embodiment, the electronic device 1100 caninclude one or more external electrical contacts, labeled in FIG. 11E asthe contact group 1110. Similarly, the stylus 1102 includes one or morecorresponding external electrical contacts, labeled in FIG. 11E as thecontact group 1112.

The contact group 1110 is configured to interface with the contact group1112 and facilitate data and/or power transactions between the stylus1102 and the electronic device 1100. Accordingly, the contact group 1110and the contact group 1112 typically have the same number of discretecontacts. In other embodiments, however, the contact group 1110 and thecontact group 1112 may have a different number of contacts.

In some embodiments, the electronic device 1100 includes one or moremagnets that are configured to attract the stylus 1102 to the electronicdevice 1100 in a manner such that the contact group 1110 interfaces(e.g., mates with) the contact group 1112, such as shown in FIG. 11F. Inother examples, the stylus 1102 may also include magnets that areconfigured to attract the stylus 1102 to the electronic device 1100.

The foregoing description of the embodiments depicted in FIGS. 11A-11Fand various alternatives and variations, are presented, generally, forpurposes of explanation, and to facilitate a general understanding ofvarious methods of charging an internal battery of a stylus. However, itwill be apparent to one skilled in the art that some of the specificdetails presented herein may not be required in order to practice aparticular described embodiment, or an equivalent thereof.

Further, although many embodiments described herein reference user inputsystems that incorporate a stylus and an electronic device that eachinclude specific hardware, this disclosure is not limited to particularapparatuses or systems. To the contrary, it may be appreciated by one ofskill in the art that the various elements disclosed herein may bemodified in a number of suitable and implementation-specific ways. Inother words, one of skill in the art may appreciate that manyembodiments described herein relate to and generally reference methodsof operating, controlling, configuring, calibrating, using, and/ormanufacturing user input systems, styluses, electronic devices, and soon. As such, FIGS. 12-24 are provided to facilitate a generalunderstanding of certain example methods described herein, although onemay appreciated that the various operations described and/or illustratedwith respect to these figures are not intended to be exhaustive in everycase.

FIG. 12 is a flow chart depicting operations of a process 1200 oflocating and estimating the angular position of a stylus touching aninput surface of an electronic device in accordance with embodimentsdescribed herein. The process 1200 can be performed by any suitableelectronic device, such as, but not limited to, the electronic device102 described in reference to FIGS. 1A-1D and/or the electronic device202 described in reference to FIGS. 2A-2F.

Generally and broadly, the process initiates at operation 1202 in whicha tip signal is received by a sensor layer of an electronic device.Next, at operation 1204, a tip signal intersection area is estimated. Inmany embodiments, the electronic device estimates the tip signalintersection area by estimating the location of each of several sensornodes (such as capacitive sensor nodes) of the sensor layer that receivethe tip signal at operation 1202.

Next, at operation 1206 a ring signal is received by the sensor layer ofthe electronic device. Next, at operation 1208, a ring signalintersection area is estimated. In many embodiments, the electronicdevice estimates the ring signal intersection area by estimating thelocation of each of several sensor nodes (such as capacitive sensornodes) of the sensor layer that receive the ring signal at operation1206.

Next, at operation 1210, the tip signal intersection area and the ringsignal intersection area are used to locate the stylus on the inputsurface and to estimate the angular position of the stylus relative tothe plane of the input surface. In many embodiments, the operation oflocating the stylus on the input surface includes estimating a Cartesiancoordinate relative to an origin point defined on the input surface. Theoperation of estimating the angular position of the stylus relative tothe plane of the input surface includes a spherical coordinate setincluding an azimuthal angle and a polar angle, relative to a vectorparallel to the plane of the input surface of the stylus and relative toa vector perpendicular (e.g., normal) to the plane of the input surfaceof the stylus, respectively.

FIG. 13 is a flow chart depicting operations of a process 1300 ofestimating a force applied by a stylus to an input surface of anelectronic device. The process 1300 can be performed by any suitablestylus, such as, but not limited to, the stylus 104 described inreference to FIGS. 1A-1D and/or the stylus 204 described in reference toFIGS. 2A-2F.

The process initiates at operation 1302 in which a reaction force isreceived at a tip (e.g., a nib) of the stylus. Next, at operation 1304,an electrical property of a force-sensitive structure mechanicallycoupled to the tip of the stylus is estimated. The electrical propertycan be resistance, capacitance, accumulated charge, inductance, or anyother suitable electrical property.

Next, at operation 1306, the estimated electrical property is correlatedto a magnitude of force, (e.g., reaction force) that is received by thetip of the stylus. The correlation operation can be performed using anynumber of suitable techniques. In some cases, the electrical propertychanges linearly with the force applied to the force-sensitivestructure, whereas in other cases, the electrical property changesexponentially with the force applied to the force-sensitive structure.

Next, at operation 1308, the estimated magnitude of the reaction forceis communicated (e.g., to an electronic device), as a magnitude of forceapplied by the stylus as a vector or scalar quantity using any suitableencoded or not-encoded format.

FIG. 14 is a flow chart depicting operations of a process 1400 ofmanufacturing a stylus such as described herein. The process initiatesat operation 1402 in which a signal generator is connected to acoordination engine. The signal generator can be a control board, suchas the control board 342 described with respect to the embodimentdepicted in FIG. 3A.

Next, at operation 1404, a flexible circuit may be coupled to the signalgenerator. In some cases, the connection between the flexible circuitand the signal generator is permanent, whereas in others, the connectionmay be removable. For example, the flexible circuit can be soldered viahot bar to the signal generator. In other cases, a connector of theflexible circuit can be attached to a port of the signal generator. Instill further cases, a port attached to the flexible circuit can beattached to a connector coupled to the signal generator.

Next, at operation 1406, the flexible circuit may be coupled to astrain-responsive element, such as the strain-sensitive electrode 338described with respect to the embodiment depicted in FIG. 3A. In somecases, the flexible circuit may bend at an angle in order to connect tothe strain-responsive element.

Next, at operation 1408, the flexible circuit may be coupled to aprocessing unit, such as the processing unit circuit board set 356described with respect to the embodiment depicted in FIG. 3A. In somecases, the flexible circuit may bend at an angle in order to connect tothe processing unit.

Next, at operation 1410, the processing unit may be coupled to a powersubsystem, such as the power control board 388 described with respect tothe embodiment depicted in FIG. 3A.

FIG. 15 is a flow chart depicting operations of a process 1500 ofexiting a low power mode of a stylus. The process 1500 can be performedby any suitable stylus, such as, but not limited to, the stylus 104described in reference to FIGS. 1A-1D and/or the stylus 204 described inreference to FIGS. 2A-2F. The process initiates at operation 1502 inwhich a force indication is received by a force-sensitive structurewithin the stylus. In this example, the stylus is in a low power mode.The force indication can be a magnitude of force estimated, such asdescribed with respect to the method depicted in FIG. 13. In othercases, the force indication may be a binary or otherwise coarseindication that a force has been received. Next, at operation 1504, thestylus exits the low power mode. Thereafter, at operations 1506 and1508, the stylus may generate the tip signal and the ring signal,respectively.

FIG. 16 is a flow chart depicting operations of a process 1600 ofentering a low power mode of a stylus. The process 1600 can be performedby any suitable stylus, such as, but not limited to, the stylus 104described in reference to FIGS. 1A-1D and/or the stylus 204 described inreference to FIGS. 2A-2F. The process initiates at operation 1602 inwhich the stylus estimates that the user has not manipulated the stylusfor at least a certain period of time (e.g., timeout period). The styluscan make this estimation based on communication (or lack thereof) withan electronic device. In other cases, the stylus can make thisestimation based on sensor data or sensor input obtained from a motionsensor within the stylus. The motion sensor can be an accelerometer,gyroscope, or any other suitable motion. In other cases, the stylus canestimate that the user has not manipulated the stylus by estimating thata force-sensitive structure within the stylus has not received a force.

After estimating that the timeout period has elapsed, the stylus canenter a low power mode. In this example, the stylus can cease generatinga tip signal, such as shown at operation 1604. Additionally, the styluscan cease generating a ring signal, such as shown at operation 1606.Thereafter, at operation 1608, the stylus enters a low power mode. Thelow power mode may be a configuration of the stylus that consumes alower amount of power than when the stylus is being actively manipulatedby a user. In some examples, more than one low power mode is possible.For example, after a first timeout is reached, the stylus can enter afirst low power mode. Thereafter, after a second timeout is reached, thestylus can enter a second low power mode.

In some cases, the low power mode or modes that are entered by thestylus can depend upon a current capacity of a battery of the stylus. Inother cases, the stylus can enter one or more low power modes afterdirect communication from an electronic device. For example, anelectronic device can send a signal to the stylus when the electronicdevice enters a program or application state that may not require or isnot configured to accept input from the stylus. In one example, anelectronic device with a touch screen may send such a signal to thestylus when keyboard input is requested from a user. In another case,the electronic device may send such a signal to the stylus when the useroperating the electronic device switches from a graphic designapplication to a photo browsing application. In still further examples,the electronic device can send such a signal to the stylus upon theelectronic device's estimation that a timeout period has elapsed.

Upon receiving such a signal from the electronic device, the stylus canenter the low power mode. In many embodiments the signal is sent fromthe electronic device to the stylus via a wireless communicationinterface, such as a Bluetooth interface, infrared interface, acousticinterface, or any other suitable wireless interface.

In other cases, the electronic device can send a signal to the styluswhen the electronic device enters a low power mode. For example, theelectronic device can send such a signal to the stylus when the useroperating the electronic device causes the electronic device to powerdown or enter a standby state. In still further embodiments, the styluscan enter a low power mode after estimating that the orientation of thestylus is beyond a certain threshold value. For example, upon estimatingthat the stylus is lying flat on a surface (e.g., polar angle is zero),the stylus can enter a low power mode. In still further embodiments, thestylus can enter a low power mode after estimating that the stylus isconnected to a power port and is receiving power, such as depicted inFIGS. 9D-9E.

FIG. 17 is a flow chart depicting operations of a process 1700 ofnotifying a user to charge a stylus. The process 1700 can be performedby any suitable stylus, such as, but not limited to, the stylus 104described in reference to FIGS. 1A-1D and/or the stylus 204 described inreference to FIGS. 2A-2F. The process initiates at operation 1702 inwhich the stylus estimates that a battery of the stylus has droppedbelow a certain minimum threshold. Next, at operation 1704, the styluscan communicate to an associated electronic device that the stylus is inneed of charging.

FIG. 18 is a flow chart depicting operations of a process 1800 ofcharging a stylus with an electronic device. The process 1800 can beperformed by any suitable stylus, such as, but not limited to, thestylus 104 described in reference to FIGS. 1A-1D and/or the stylus 204described in reference to FIGS. 2A-2F. The process initiates atoperation 1802 in which the stylus estimates that the stylus has beenplugged into a data port connector and is ready to receive power. Next,at operation 1804, the stylus can enter a constant current fast chargingmode. In this example, a battery within the stylus can be rapidlycharged.

In some embodiments, the stylus can illuminate an indicator in order toconvey information related to the current charge of the battery. Forexample, the stylus can illuminate an indicator with a red or orangecolor when the battery is charging. Once the battery is charged, thestylus can illuminate the indicator with a green color. In otherexamples, the stylus can periodically adjust the brightness of theindicator. In other examples, the stylus can animate the indicator(e.g., increasing or decreasing the brightness thereof in a breathingpattern) to convey to a user that the stylus is charging.

FIG. 19 is a flow chart depicting operations of a process 1900 ofnotifying a user that a stylus is charged. The process 1900 can beperformed by any suitable stylus, such as, but not limited to, thestylus 104 described in reference to FIGS. 1A-1D and/or the stylus 204described in reference to FIGS. 2A-2F. The process initiates atoperation 1902 in which the stylus estimates that the battery containedtherein is fully or nearly fully charged. Next, at operation 1904, thestylus communicates to an electronic device that the stylus is chargedusing any suitable encoded or not-encoded format.

FIG. 20 is a flow chart depicting operations of a process 2000 ofoperating an electronic device in either a touch input mode or a stylusinput mode. The process 2000 can be performed by any suitable electronicdevice, such as, but not limited to, the electronic device 102 describedin reference to FIGS. 1A-1D and/or the electronic device 202 describedin reference to FIGS. 2A-2F.

The process initiates at operation 2002 in which the electronic deviceenters a touch input mode. When in the touch input mode, the electronicdevice may be configured to receive single touch or multi-touch inputfrom a user. In order to receive such input, the electronic device can,at operation 2004, configure a coordination engine (such as thecoordination engine 220 described in reference to FIGS. 2A-2F) to detectcapacitive interference that results from a user touch.

Next, at operation 2006, the electronic device enters a stylus inputmode. When in the stylus input mode, the electronic device may beconfigured to locate and estimate the angular position of one or morestyluses. In order to receive such input, the electronic device can, atoperation 2008, configure the coordination engine to detect a ring fieldsignal and a tip field signal.

FIG. 21 is a flow chart depicting operations of a process 2100 ofoperating an electronic device in both a touch input mode and a stylusinput mode. The process 2100 can be performed by any suitable electronicdevice, such as, but not limited to, the electronic device 102 describedin reference to FIGS. 1A-1D and/or the electronic device 202 describedin reference to FIGS. 2A-2F. The process initiates at operation 2102 inwhich the electronic device enters a hybrid input mode. When in thehybrid input mode, the electronic device may be configured to locate andestimate the angular position of one or more styluses, in addition toreceiving touch input (e.g., single touch or multi-touch) from a user.In order to receive such hybrid input, the electronic device can, atoperation 2104, configure the coordination engine to detect a ring fieldsignal and a tip field signal in addition to capacitive interferencethat results from a user touch.

FIG. 22 is a flow chart depicting operations of a process 2200 ofcompensating for tilt-induced offset when locating a stylus on an inputsurface. The process 2200 can be performed by any suitable electronicdevice, such as, but not limited to, the electronic device 102 describedin reference to FIGS. 1A-1D and/or the electronic device 202 describedin reference to FIGS. 2A-2F.

The method depicted in FIG. 22 may be suitable for use in embodiments inwhich the input surface of the electronic device is separated by somedistance from the sensor layer of the electronic device that detects thepresence of a tip field and a ring field of a stylus such as describedherein. As may be appreciated, the distance separating the input surfacefrom the sensor layer may cause the tip field intersection area to shiftbased on the polar angle and/or the azimuthal angle of the stylus. Thisoffset resulting from the distance between the input surface and thesensory layer is generally referred to as “tilt-induced offset.”

The process initiates at operation 2202 in which the angular position ofthe stylus is estimated. Next, at operation 2204, the electronic devicecorrects the estimated location of the stylus based on the angularposition of the stylus.

FIG. 23 is a flow chart depicting operations of a process ofmanufacturing a blind cap incorporating a pressure vent. The method 2300begins at operation 2302 in which a blind cap is molded. The blind capcan be molded using any suitable process, such as, but not limited to,injection molding, transfer molding, blow molding, and so on. In manyembodiments, the blind cap may be molded with internal features. Forexample, in one embodiment, a series of spokes may be molded into aninterior top surface of the blind cap. The spokes may be radiallydistributed around the longitudinal axis of the blind cap.

Next, at operation 2304, the blind cap may be machined. In particular,one or more channels can be machined into a top portion of the blindcap. In one embodiment, the channel has a generally circular shape,although this is not required. In many embodiments, the channel isformed to a depth that at least partially forms an aperture through theblind cap that connects the internal volume of the blind cap to theexterior. For example, if the blind cap were molded with a series ofinternal spokes, the channel may be formed to expose the space betweenthose spokes, while retaining the spokes in place.

Next, at operation 2306, one or more pressure vents may be machined intothe base of the channel formed at operation 2304. In some cases,machining of pressure vents may not be required.

FIG. 24 is a flow chart depicting operations of a process of operating auser input system in more than one mode. The method may be performed bya stylus such as described herein or an electronic device such asdescribed herein. The method, generally and broadly, relates to powersavings in a stylus that may be achieved by selectively deactivatingfeatures of the stylus that are not specifically required given aparticular operational state of the stylus at a particular time. In onespecific example, a stylus may be operable in a mode that does notrequire the angular position of the stylus to be determined, such aswhen using the stylus to select user interface elements on a display.When in such an operational mode, the ring field of the electronicdevice may be deactivated to save power within the stylus.

In other cases, power savings in the stylus may be achieved byselectively deactivating features of the stylus that are notspecifically required given a particular input requirement of anelectronic device at a particular time. In one specific example, anelectronic device may be operable in a mode that does not require theangular position of a stylus to be determined, such as when theelectronic device is configured to receive only position information(e.g., drawing a line of constant thickness). When in such anoperational mode, the ring field of the electronic device may bedeactivated to save power within the stylus. FIG. 24 depicts such amethod.

The method 2400 begins at operation 2402 in which an input type isdetermined. An input type may be related to an operational state of theelectronic device. For example, an electronic device may be operable ina mode that interprets location and angular position informationobtained from a stylus as input from a simulated pencil. In thisexample, the location of the stylus may correspond to a path of asimulated pencil line or stroke and the angular position information maycorrespond to the width and/or shading qualities of that pencil line orstroke. This mode may be referred to as “pencil input mode.”

In another example, an electronic device may be operable in a mode thatinterprets only the location information from a stylus as input from asimulated pen. In this example, the location of the stylus correspondsto a path of the simulated pen; angular position information does notaffect the width or quality of the line in any manner. This mode may bereferred to as a “pen input mode.”

In yet another example, an electronic device may be operable in a modethat interprets only the location information from a stylus as inputfrom a user's finger. In this example, the location of the styluscorresponds to a touch input; angular position information does notaffect the touch input. This mode may be referred to as a “touch inputmode.”

In further embodiments, the electronic device may be operable in anumber of additional modes including, but not limited to, fountain peninput mode, highlighter input mode, charcoal input mode, palate knifeinput mode, brush input mode, chisel input mode, user interfaceselection input mode, gaming input mode, joystick input mode, and so on.Some of these input modes may require both location and angular positioninformation while others only require location information.

The input mode of the electronic device may correspond to an input typeof the stylus. The stylus may be operable to provide two types of input:location-only input and location and angular position input.

Accordingly, at operation 2402, the method 2400 determines what inputtype is required or requested at a particular time. Next at operation2404, the stylus may determine whether the determined input typerequires both location information and angular position information. Ifboth are required, the method 2400 continues to operation 2406 at whichthe stylus activates both the ring field and the tip field. In thealternative that only location information is required, the method 2400continues to operation 2408 at which the stylus activates only the tipfield, deactivating the ring field.

One may appreciate that although many embodiments are disclosed above,that the operations and steps presented with respect to methods andtechniques described herein are meant as exemplary and accordingly arenot exhaustive. One may further appreciate that an alternate step orderor fewer or additional steps may be implemented in particularembodiments.

Although the disclosure above is described in terms of various exemplaryembodiments and implementations, it should be understood that thevarious features, aspects and functionality described in one or more ofthe individual embodiments are not limited in their applicability to theparticular embodiment with which they are described, but instead can beapplied, alone or in various combinations, to one or more of theembodiments of the invention, whether or not such embodiments aredescribed and whether or not such features are presented as being a partof a described embodiment. Thus, the breadth and scope of the presentinvention should not be limited by any of the above-described exemplaryembodiments but is instead defined by the claims herein presented.

What is claimed is:
 1. A stylus comprising: a body; a force sensordisposed within the body; a tubular shield mechanically coupled to theforce sensor; a signal line within the tubular shield; a first electricfield generator electrically coupled to a signal line and coaxiallyaligned with a longitudinal axis of the body; and a second electricfield generator separated from the first electric field generator. 2.The stylus of claim 1, wherein a central axis of the second electricfield generator is coaxially aligned with the longitudinal axis.
 3. Thestylus of claim 1, wherein: the body comprises a tip end; and the forcesensor is disposed adjacent to the tip end.
 4. The stylus of claim 1,wherein the tubular shield is configured to translate along thelongitudinal axis of the body.
 5. The stylus of claim 1, wherein: thetubular shield comprises a tray section; the stylus further comprises acontrol board electrically coupled to the signal line; and the controlboard is mechanically coupled to the tray section.
 6. The stylus ofclaim 5, wherein the control board is configured to apply an electricalsignal to the first electric field generator via the signal line tocause the first electric field generator to generate an electric field.7. The stylus of claim 5, wherein the tubular shield comprises: a hollowsection extending from the tray section; wherein the signal line isdisposed within the hollow section.
 8. The stylus of claim 7, whereinthe hollow section of the tubular shield is formed from metal.
 9. Thestylus of claim 7, wherein the hollow section of the tubular shieldcomprises an electrically insulating portion.
 10. The stylus of claim 5,wherein: the tray section of the tubular shield is mechanically coupledto the force sensor; and the force sensor is mechanically coupled to thebody of the stylus.
 11. The stylus of claim 1, wherein the force sensorcomprises: a cantilevered leg mechanically coupled to the body; a baseportion coupled to the cantilevered leg; and a strain sensor coupled tothe cantilevered leg.
 12. The stylus of claim 11, wherein thecantilevered leg is formed from metal.
 13. The stylus of claim 11,wherein the tubular shield is mechanically coupled to the base portion.14. The stylus of claim 11, wherein the strain sensor is electricallycoupled to a control board disposed within a tray section of the tubularshield.
 15. The stylus of claim 1, further comprising a second signalline within the tubular shield, isolated from the first signal line. 16.The stylus of claim 15, wherein: the signal line is a first signal line;the second signal line is electrically coupled to the second electricfield generator; and the second signal line is electrically isolatedfrom the first signal line.
 17. The stylus of claim 1, wherein thesecond electric field generator comprises an electrically-conductivering.
 18. The stylus of claim 1, wherein the second electric fieldgenerator comprises an electrically-conductive cylinder.
 19. The stylusof claim 1, wherein the second electric field generator is configured togenerate a substantially spherical electric field extending outwardlyfrom a tip end of the body.
 20. The stylus of claim 19, wherein thefirst electric field generator comprises: a bulb oriented outwardly fromthe tip end; and a root connected to the bulb and oriented inwardly withrespect to the body of the stylus.